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Down Syndrome

We specialise in advanced screening, NIPT, expert scans, and addressing all concerns related to Down syndrome during pregnancy.

We provide a second opinion ultrasound on findings associated with Down syndrome.

Down syndrome is trisomy 21: Key Information

Down syndrome is trisomy 21. This common genetic condition happens when there’s an extra copy of chromosome 21 in a baby’s cells. This extra genetic material leads to certain physical, developmental and intellectual differences. Down syndrome is not inherited and occurs randomly. 

At present, NIPT stands as the most advanced screening for Down syndrome, available starting from 10 weeks of pregnancy. NIPT demonstrates an exceptionally high negative predictive value for Down syndrome, indicating that if the test shows a low chance, the likelihood of delivering a baby with Down syndrome is exceedingly slim.

The London Pregnancy Clinic is a leading provider of advanced NIPT services in the UK.

Down syndrome:

What assistance can we provide?

NIPT: best Down syndrome test

NIPT stands out as the best Down syndrome screening test due to its high negative predictive value—meaning its effectiveness in ruling out the condition—coupled with a notably low rate of false positive results. NIPT offers the advantage of delivering results as early as 10 weeks into the pregnancy.

At the London Pregnancy Clinic, we exclusively utilise advanced and dependable brands of NIPT known for their reliability. Our NIPT procedures demonstrate high reliability, maintaining an inconclusive results rate (known as no-call results) of only around 2%.

The PerenatalSafe Test, conducted here in the UK, not only guarantees accuracy but also boasts a notably swift turnaround time, currently establishing itself as the premier choice for NIPT in London.

Scan and NIPT for Soft Markers

NIPT is the safest option in the case of Down syndrome-related findings.

Fetal ultrasound features linked to Down syndrome, referred to as soft markers or anatomical variants (see below), are minor physical characteristics occasionally spotted during prenatal scans. Though they aren’t structural anomalies, their presence may marginally elevate the statistical chance of Down syndrome. Yet, it’s essential to stress that these markers don’t confirm the diagnosis; they simply suggest a higher probability.

These indicators of Down syndrome are frequently observed during healthy pregnancies. While they might capture the attention of sonographers and doctors during ultrasound examinations, most pregnancies displaying these markers don’t yield babies with Down syndrome or any other chromosomal abnormalities.

When healthcare providers evaluate these findings concerning each pregnancy, they may contemplate additional testing tailored to specific risk factors and circumstances. Procedures such as chorionic villus sampling (CVS) or amniocentesis might be necessary to rule out Down syndrome.

Alternatively, although not diagnostic, NIPT can significantly diminish the likelihood of Down syndrome. NIPT boasts an exceptionally high negative predictive value. At the London Pregnancy Clinic, we conduct a second opinion assessment of fetal ultrasound features and offer reliable NIPT services.

Increased NT: second opinion scan

Second Opinion Nuchal Translucency Scan and Early Fetal Echocardiography.

An elevated NT reading can be an anxious discovery for parents as it may suggest potential health concerns for the baby, such as the likelihood of Down syndrome or heart anomalies. To assess the probability of Down syndrome, NT measurements are combined with blood tests for PAPP-A and HCG. Unfortunately, obtaining results from these tests often involves a delay due to logistical reasons, causing additional stress for parents awaiting crucial information.

We understand the strain this delay can cause and are here to help. In such cases, early fetal echocardiography, which encompasses an early anomaly scan, is recommended for babies with increased NT. This assessment can effectively rule out most severe cardiac anomalies or identify heart defects that may be associated with Down syndrome or other chromosomal anomalies.

Moreover, our detailed examination includes a thorough assessment of major structural anomalies linked to chromosomal defects. We meticulously measure the fluid collection at the back of the fetal neck to precisely gauge the NT. While the ideal time for a Down syndrome-related ultrasound is typically around the 13th week, in instances of increased NT, an expert scan at the earliest convenience is essential.

At the London Pregnancy Clinic, we strive to accommodate concerned parents promptly. We often offer same-day or next-day appointments for second-opinion nuchal translucency scans, which encompass early fetal echocardiography. This approach aims to provide reassurance and comprehensive evaluation for expectant parents during such critical moments.

High chance NIPT: expert fetal scan

Early Fetal Echocardiography for High Risk NIPT results.

When a Non-Invasive Prenatal Test (NIPT) indicates a high probability of Down syndrome, various terms like ‘high chance’, ‘high risk’, or ‘detected’ are used by different providers. While these terms can be worrying, they typically suggest a very high likelihood (around 90%) that the baby may have Down syndrome. However, it’s important to remember that NIPT, despite its high accuracy, is not a diagnostic test. This means there is still a chance (approximately 10%) that the baby might not be affected by the condition.

If your NIPT results show a high probability for Down syndrome, the next step recommended by medical professionals globally is to undergo an invasive diagnostic test, such as Chorionic Villus Sampling (CVS) or amniocentesis. These tests are crucial to confirm the NIPT findings, and we strongly advise them before making any decisions about the pregnancy. Skipping this confirmatory step could lead to unintended consequences, like terminating a normal pregnancy based on a false-positive NIPT result.

Arranging and waiting for CVS or amniocentesis can be a tough process, often taking time, with a further 2-3 working days needed for results. We understand that this waiting period can be particularly stressful for parents. During this time, many parents wish to learn as much as possible about their baby’s condition, especially concerning heart health, due to the link between Down syndrome and heart anomalies.

In these situations, a detailed ultrasound is invaluable in evaluating the baby’s physical condition. Early fetal echocardiography, which we offer, is especially helpful in ruling out major heart defects and other structural problems. At London Pregnancy Clinic, we are committed to supporting parents through these anxious times. We frequently provide same-day or next-day appointments for second-opinion scans, including early fetal echocardiography. We aim to provide you with a comprehensive fetal evaluation during these crucial moments in your pregnancy journey.

Scan for baby diagnosed with Down syndrome

Support Following a Trisomy 21 Diagnosis

Learning that your baby may have trisomy 21 (Down syndrome) through CVS (Chorionic Villus Sampling) or amniocentesis can be an emotional experience. To confirm this diagnosis quickly, a special test called quantitative fluorescent-polymerase chain reaction (QF-PCR) is used. This test looks for the extra chromosome 21 in the baby’s cells and usually provides results within three working days.

However, QF-PCR has its limitations. In certain situations, especially for conditions like Down syndrome, a more detailed chromosome examination (karyotype analysis) is needed. This analysis helps to understand the specific chromosome changes and the chance of them occurring again in future pregnancies. It usually takes about 2-3 weeks to get these results.

Sometimes, QF-PCR may indicate trisomy 21, but the ultrasound might not show typical Down syndrome signs, like the baby not having a high nuchal translucency (NT) measurement. In these cases, there’s a small chance the genetic results might not fully represent the baby’s condition. If the ultrasound appears normal, it is generally recommended to wait for the karyotype results before making any decisions.

Awaiting the final results from Chorionic Villus Sampling (CVS), particularly when a comprehensive chromosome analysis (karyotype) is involved, can be a time of significant emotional strain. This 2-3 week waiting period not only extends the time of uncertainty but also has crucial implications if the family is considering the option of pregnancy termination. As the gestation period lengthens, the options and methods for termination, should that be the chosen path, become more limited and potentially more complex, adding an additional layer of emotional and psychological burden for the patient and their family.

It’s also important to remember that while a positive result from CVS or amniocentesis confirms the genetic diagnosis of trisomy 21, it doesn’t provide a full picture of the baby’s physical development. This includes crucial aspects such as heart health or specific facial characteristics associated with Down syndrome, like an absent nasal bone.

To help provide a more comprehensive understanding, we conduct an expert ultrasound examination. In the first trimester, this typically includes both transabdominal and transvaginal scans to thoroughly assess the heart and all other organs of the baby. These detailed scans can offer more clarity about the baby’s physical condition and help in making informed decisions. Particularly, this scan can be invaluable for parents who choose to continue a pregnancy following a Down syndrome diagnosis and are seeking reassurance about the overall health of their baby.

Our Early Fetal Echocardiography examines all the baby’s organs, with special attention to the heart. This can be done as early as 12 weeks, right after receiving PCR results. Additionally, for parents eager to see their baby, we offer the option of a 4D ultrasound as part of this early screening. Our high-resolution equipment allows for high-quality 3D imaging, though success depends on the baby’s position and may not always be possible.

At the London Pregnancy Clinic, our priority is to support and guide you through this period with care and compassion. We’re here to provide you with detailed information and reassurance every step of the way.

Down syndrome: counselling

Counselling regarding antenatal management and delivery options for pregnancies with Down syndrome by Mr Dan Stott.

A significant number of parents, upon receiving a positive diagnosis of Down syndrome through procedures like CVS or amniocentesis, choose to continue with the pregnancy. Others who have a high likelihood of trisomy 21 as indicated by NIPT or combined screening test (e.g., 1 in 5) are positive about Down syndrome and may opt not to undergo further testing due to the associated risk of miscarriage with invasive procedures. We fully support their decisions and aim to provide them with a supportive and smooth journey.

Pregnancies involving trisomy 21 often encounter more complications compared to those with typical chromosomes. There are various reasons for this, but two primary factors stand out:

  1. Complications due to distinctive physical features of a baby with Down syndrome within the womb, such as fetal anomalies like duodenal atresia and heart defects. Duodenal atresia can lead to severe or tension polyhydramnios, characterized by excess fluid around the baby. In some rare instances, excess fluid may require drainage via amniocentesis to alleviate maternal discomfort. Even without duodenal atresia, babies with Down syndrome can develop polyhydramnios, possibly due to factors like enlarged tongue (macroglossia) and reduced muscle tone (hypotonia), which can impact swallowing.

  2. Problems associated with placental function. The abnormal genetic code in trisomy 21 might affect the functioning of the placenta. Consequently, trisomy 21 fetuses often experience issues like placental insufficiency, fetal growth restriction (FGR), and significant abnormalities in Doppler blood flow. Some may even face the unfortunate possibility of intrauterine demise.

  3. Additionally, rare complications like Transient Abnormal Myelopoiesis (TAM) of Down syndrome, previously termed transient leukaemia due to its resemblance, may rarely manifest in the womb.

Addressing these complex issues requires specialised counselling and management plans for pregnancies diagnosed with trisomy 21 or those with high suspicion of the condition. This involves a series of repeated scans to monitor the baby’s well-being, typically carried out through Fetal Medicine Units within the NHS.

For those seeking further information and guidance on the antenatal management of pregnancies affected by Down syndrome, as well as delivery options, our Fetal Medicine and Obstetrics consultant, Mr. Dan Stott, is readily available to assist.

With a particular focus on managing complex pregnancies, Mr. Stott brngs extensive experience to the table. He has recently completed a significant research project, drawing from a decade of antenatal managing trisomy 21 pregnancies at UCLH, which provides unique insights into this field.

Down syndrome in previous pregnancy

Support and Guidance for New Pregnancies After Trisomy 21

If you’re preparing for a new pregnancy after a previous one was affected by trisomy 21 (Down syndrome), it’s natural to feel a mix of emotions, from anxiety to hope. We understand that, especially for those who’ve experienced false-negative combined screening tests, had a delayed diagnosis or were surprised by the birth of a baby with Down syndrome, the journey to a subsequent pregnancy can be filled with worry.

It’s important to remember that Down syndrome is usually not passed down through families. If you’ve had a pregnancy affected by Down syndrome, the chances are still very good that your next pregnancy will result in a healthy baby.

To offer peace of mind and reassurance, we recommend considering an early scan and blood test at 10 weeks, known as Non-Invasive Prenatal Testing (NIPT). In our London Pregnancy Clinic, we perform advanced 10 Week Scan and NIPT.  This early test checks both the physical development and genetic makeup of the baby and is known for its high accuracy in detecting Down syndrome.

At our clinic, we offer various advanced NIPT options, with PrenatalSafe being a popular choice. This test stands out for its quick results, low need for repeat samples, and a small chance of inconclusive results. It’s also known for having a very low rate of missing Down syndrome (false-negative rate). In fact, large studies involving over 750,000 NIPT tests by different NIPT biotechnologies have shown that only 0.6% of Down syndrome cases are missed by these tests.

While NIPT is highly accurate, it’s also important to know that no test is perfect. There are rare occasions where NIPT might not detect certain conditions. That’s why we’re here to discuss all available screening options with you, ensuring you’re fully informed and supported in your decision-making process.

If you’ve previously experienced a trisomy 21 pregnancy, our advice is not to wait until the standard 12-week mark. Early reassurance through our 10 Week Scan and NIPT services can be invaluable, helping you approach your new pregnancy journey with more confidence and peace of mind.


Down syndrome 4D scan at 26 week

Ultrasound signs of Down syndrome during pregnancy

Fetal anomalies linked to Down syndrome may include physical defects affecting different organs and systems. Common anomalies noticed in fetuses with Down syndrome might affect the heart (e.g., atrioventricular septal defects), gastrointestinal tract (such as duodenal atresia), and other structural abnormalities. The severity of these anomalies can vary, and not all fetuses with Down syndrome will display them.

Fetal signs of Down syndrome called soft markers or anatomical variants, are minor physical features occasionally detected during prenatal scans. While they aren’t structural anomalies, their presence might slightly raise the statistical likelihood of Down syndrome. However, it’s crucial to emphasize that these markers don’t confirm the diagnosis; they simply hint at a higher probability. 

These signs of Down syndrome are common and are often observed in healthy pregnancies. While they might catch the attention of sonographers and doctors during ultrasound examinations, the majority of pregnancies with these markers don’t result in babies with Down syndrome or any other chromosomal abnormalities.

When healthcare providers assess these findings in the context of the individual pregnancy they may consider additional testing tailored to specific risk factors and circumstances. Tests like NIPT, chorionic villus sampling (CVS), or amniocentesis may be needed to either lower the likelihood of Down syndrome or to conclusively rule it out.


atrioventricular septal defect

An atrioventricular septal defect (AVSD) is a heart defect where there’s a hole in the middle of the heart involving all four chambers and two main valves. This large hole disrupts blood circulation within the heart. AVSD is considered one of the more prevalent and characteristic heart defects in babies born with Down syndrome, occurring in around 40-50% of them.


ventricular septal defect

A ventricular septal defect (VSD), often referred to as a ‘hole in the heart,’ is a condition characterized by an abnormal opening between the heart’s lower chambers. Among individuals with Down syndrome, VSD is a prevalent congenital heart defect, occurring more frequently than in the wider population.

Duodenal atresia

Double bubble

Duodenal atresia is a blockage in the first part of the small intestine, causing feeding difficulties in newborns. A characteristic ‘double bubble’ appearance on ultrasounds often identifies it. There’s a significantly increased occurrence of duodenal atresia in babies with Down syndrome compared to those without, suggesting a potential genetic link between the two conditions.


Dilated brain ventricles

Ventriculomegaly describes enlarged brain ventricles and may occasionally be observed in Down syndrome cases during pregnancy. It’s considered when the ventricular diameter measures 10 mm or more. While not a specific indicator of Down syndrome, ventriculomegaly increases the likelihood of chromosomal or genetic conditions.

Fetal hydrops

Hydrops fetalis

Fetal hydrops, or hydrops fetalis, involves abnormal fluid accumulation in multiple fetal areas. It’s a serious condition, not directly linked to Down syndrome, although some babies with Down syndrome might develop fetal hydrops or show similar features during different stages of pregnancy. Fetal hydrops can stem from various factors beyond chromosomal abnormalities, including genetic syndromes, infections or fetal heart and lung issues.

High NT

Increased nuchal translucency

Increased nuchal translucency (NT) occurs when the fluid space at the back of a fetus’s neck measures above the 95th centile during a prenatal ultrasound at 11-13 weeks. It’s a significant and widely recognized soft marker for Down syndrome, hinting at an increased likelihood of chromosomal abnormalities or other health conditions. However, it doesn’t offer a definite diagnosis. Clinicians might use this measurement alongside other tests to assess the probability of Down syndrome.

Nuchal Fold

Increased NF thickness

In the second trimester, a thickened nuchal fold (NF) is identified when the skin at the back of a fetus’s neck measures 6mm or more during a 20 week anomaly scan. It is a notable and commonly acknowledged soft marker for Down syndrome, suggesting an elevated chance of chromosomal abnormalities. Nevertheless, it does not provide a definitive diagnosis. Antenatal care providers may consider this measurement alongside other tests to evaluate the likelihood of Down syndrome.

Absent Nasal Bone

Hypoplastic Nasal Bone (NB)

An absent or underdeveloped nasal bone (NB) in a fetus during prenatal ultrasounds is considered a soft marker for Down syndrome. The absence of a nasal bone is a distinct characteristic often seen in Down syndrome during both the first trimester (11-13 weeks) and the second trimester (20 weeks) ultrasound examinations. While nasal bone absence doesn’t confirm the condition, it suggests an increased chance of chromosomal abnormalities, especially Down syndrome. 


Aberrant Right Subclavian Artery

The aberrant right subclavian artery (ARSA) is an anatomical variation in the arteries that supply the right arm and upper body, typically found in around 1% of the population. ARSA is more frequently noticed in Down syndrome cases during antenatal scans; however, its presence alone isn’t confirmatory of the diagnosis. While most healthcare providers don’t advocate using this condition for screening, further tests may be necessary to confirm or dismiss Down syndrome if ARSA is detected.


Round shape of the head

Brachycephaly refers to a shorter and broader, or rounder, head shape occasionally observed in fetuses with Down syndrome. However, this particular head shape alone isn’t conclusive evidence of Down syndrome, as it can also be present in babies without the condition. Brachycephaly is regarded as a less distinct marker for chromosomal anomalies.

Ductus venosus flow

reversed a-wave in DV

The ductus venosus (DV) is a fetal blood vessel allowing oxygenated blood to bypass the liver and flow into the heart. The “a-wave” signifies a particular blood flow pattern in the DV during the fetal heartbeat. During the 11-13 week scan, abnormal a-wave or high PI (pulsatility index) in the ductus venous flow might be observed in some Down syndrome cases. DV flow is not a conclusive diagnostic marker and is assessed alongside other tests for a comprehensive evaluation.

Echogenic Bowel

Hyperechogenic Bowel

Hyperechogenic bowel, also called echogenic bowel, shows up as a brighter fetal bowel on prenatal ultrasound. While it’s seen as a potential marker for Down syndrome, it doesn’t confirm the condition on its own. In most cases, babies with echogenic bowel don’t have Down syndrome. However, additional tests might be necessary to investigate potential causes or other chromosomal abnormalities associated with this finding.

Intracardiac Echogenic Focus

ICEF – golf ball

An intracardiac echogenic focus (ICEF), often described as a “golf ball” appearance in the fetal heart during ultrasounds, is a small, bright spot. Echogenic focus is among the oldest markers of Down syndrome, identified over 30 years ago. ICEF is quite common but seen in only a small fraction of pregnancies with chromosomal abnormalities. While some medical professionals still regard “golf ball” as a soft marker for Down syndrome, its clinical significance is highly debated.

Single umbilical artery


A single umbilical artery (SUA) occurs when the umbilical cord has one artery instead of the usual two. While a single umbilical artery can be considered a soft marker during prenatal screenings, it’s more commonly associated with Edwards syndrome (Trisomy 18) or Patau syndrome (Trisomy 13) rather than Down syndrome (Trisomy 21). Healthcare providers might recommend further assessments to evaluate the overall risk of chromosomal abnormalities.


Increased amniotic fluid volume

Polyhydramnios is when there’s too much amniotic fluid around the fetus during pregnancy. Polyhydramnios can occur in pregnancies with Down syndrome, but increased fluid levels can also result from other factors like fetal structural anomalies or maternal health conditions. Often, polyhydramnios has no apparent cause and leads to the birth of healthy babies.

Prenasal Thickness

Nose skin oedema

Prenasal thickness or nose skin oedema refers to the thickening or swelling of the skin over the nasal bone or nasal bridge of the fetus seen during prenatal ultrasound exams. This ultrasound feature is among the more recent findings associated with Down syndrome. This increased thickness or oedema is frequently noticed in fetuses with Down syndrome, serving as a soft marker for the condition.

Renal pelvis dilatation (RPD)

Mild Dilatation of Kidney Pelvis

Renal pelvis dilatation (RPD) or mild dilatation of the kidney pelvis shows a slight enlargement of the area that collects urine in the kidney during prenatal ultrasounds. While sometimes considered a soft marker for Down syndrome, this finding is relatively common and can occur in pregnancies without chromosomal abnormalities. Further assessments are usually recommended for a more thorough evaluation.

Short femur

Short FL

Shortening of the femur, detected during prenatal ultrasounds, suggests the fetal thigh bone (femur) is shorter than expected for the pregnancy stage. In most cases, a short femur is a normal variation and doesn’t indicate any health issue or abnormality in babies.  Regarding Down syndrome, a shortened femur is seen as a soft marker. Shortened femur length can also occur for various reasons unrelated to chromosomal abnormalities and is found in some pregnancies without Down syndrome.

Short humerus

Short HL

During prenatal ultrasounds, if the fetal arm bone (humerus) appears shorter than expected for the pregnancy stage, it’s termed as shortening of the humerus. In the majority of cases, a shorter humerus is considered a normal variation and doesn’t suggest any health problems in babies. Concerning Down syndrome, a shortened humerus is regarded as a soft marker. However, a shortened humerus can also happen due to reasons not related to chromosomal abnormalities and might be present in pregnancies without Down syndrome.

Tricuspid regurgitation

Leaking tricuspid valve, TR

Tricuspid regurgitation (TR) is when blood leaks backwards through the tricuspid valve in the heart, sometimes noticed during 11-13 week prenatal ultrasounds. In relation to Down syndrome, TR is viewed as a soft marker. Its presence might slightly increase the chance of chromosomal abnormalities, but TR alone doesn’t confirm Down syndrome. TR can happen for reasons unrelated to chromosomal conditions and might be seen in pregnancies without Down syndrome.

Frequently Asked Questions

Your questions answered

1 in 377 births is an incidence of Down syndrome. Is it true?

Yes, in the last few years, the prevalence of Down syndrome in the UK has been relatively high. 

It is official data from The National Congenital Anomaly and Rare Disease Registration Service (NCARDRS) regarding Down syndrome total births in  England.

Can you make Down syndrome definition simple?

Define down syndrome:

Down syndrome is a condition where someone has an extra chromosome. Chromosomes are bundles of genes that determine how a baby’s body forms and functions before and after birth. Down syndrome results from a random occurrence of an extra chromosome 21 during the formation of the egg or sperm. This extra chromosome 21 affects a baby’s body and brain development, leading to physical and mental differences.

Typically, a baby is born with 46 chromosomes, but those with Down syndrome have an additional copy of chromosome 21, also known as Trisomy 21. This extra chromosome alters the baby’s physical and cognitive development, leading to both intellectual and physical challenges.

Individuals with Down syndrome often exhibit an IQ in the mildly-to-moderately low range and typically have delayed speech compared to other children.

Down syndrome description:

Typical physical characteristics associated with Down syndrome include:

  • A flat profile, especially in the nose bridge
  • Almond-shaped eyes with an upward slant
  • Specks in the iris of the eye
  • Protruding tongue
  • Small ears
  • Short neck
  • Small hands and feet
  • A single crease across the palm (palmar crease)
  • Shorter height during childhood and adulthood
  • Poor muscle tone
  • Loose joints
Down syndrome or trisomy 21, which term is correct?

Down syndrome and trisomy 21 are indeed synonyms. Down syndrome is associated with the genetic condition resulting from an extra copy (or partial extra copy) of chromosome 21 in the cells, hence the term “trisomy 21.” Both terms refer to the same genetic abnormality and are used interchangeably to describe this condition.

In our days, there has been discussion within the medical and scientific communities about utilizing more precise and descriptive terminology for various conditions, including Down syndrome. “Trisomy 21” refers to the underlying genetic cause of Down syndrome.

This shift towards using “trisomy 21” as an alternative term for Down syndrome aims to provide a more accurate and genetics-based description of the condition. By directly referencing the chromosomal abnormality, this term clarifies the specific genetic mechanism that leads to the characteristic features and health outcomes associated with Down syndrome.

While “Down syndrome” remains the commonly used and recognized term in clinical and public spheres, the consideration of “trisomy 21” reflects the ongoing efforts to use terminology that aligns more closely with the scientific understanding of the condition’s genetic basis.

However, accepting and adopting terminology often takes time and requires consensus within the medical and broader communities. Therefore, both terms are used, with “Down syndrome” being more prevalent and widely understood by the general population.

What is Down syndrome chromosome?

Down syndrome is primarily characterized by an extra chromosome, specifically an additional copy of chromosome 21. Typically, humans possess 46 chromosomes, but in the case of Down syndrome, there’s an extra copy of chromosome 21, resulting in a total of 47 chromosomes. This additional genetic material can lead to the developmental and physical characteristics associated with Down syndrome. The condition is often referred to as “trisomy 21” due to the presence of this extra chromosome, which is responsible for the unique features and traits observed in individuals with Down syndrome.

Different types of Down syndrome explained

Different types of Down syndrome result from various causes of trisomy 21. There are three main types of Down syndrome:

  1. Trisomy 21: This is the most common form, occurring in about 95% of cases. It happens when there’s an additional copy of chromosome 21 in every cell, causing the characteristic traits of Down syndrome.
  2. Translocation Down syndrome: Approximately 3-4% of Down syndrome cases are due to translocation. This type occurs when extra genetic material from chromosome 21 attaches to another chromosome. The total number of chromosomes remains 46, but the additional chromosome 21 material can lead to Down syndrome features. This form can be inherited or arise spontaneously.
  3. Mosaic Down syndrome: Mosaic Down syndrome is relatively rare, constituting about 1-2% of all cases of Down syndrome. This variation arises from a mixture of cells, some containing the usual two copies of chromosome 21 and others having three copies. People with mosaic Down syndrome may show a diverse range of symptoms, depending on the distribution and proportion of affected cells in their body.

Rare forms of Down syndrome, such as isochromosome 21q, also exist. Although uncommon, isochromosome 21q can be associated with false-negative results in cell-free DNA prenatal screening for Down syndrome.

What type of Down syndrome test can I do while pregnant?

Expecting a child comes with many joys and some uncertainties. One way to support a healthy pregnancy journey is through prenatal screenings for Down syndrome, which offer valuable insights into your baby’s health. Here’s a brief guide to the tests available:

  • Non-Invasive Prenatal Testing (NIPT): This blood test is a less invasive option, analyzing cell-free DNA from the placenta present in the mother’s bloodstream. It’s known for its high accuracy and low false-positive rates in detecting Down syndrome.

  • Combined Screening Test (CST): This two-part test includes a blood sample (to measure PAPP-A and hCG levels) and an ultrasound scan (to assess nuchal translucency). The combined results give a probability assessment for Down syndrome.

  • Quadruple Test: Conducted through a blood sample, this test checks levels of AFP, hCG, uE3, and Inhibin-A. It’s less precise than Combined Test but still provides a risk evaluation for Down syndrome.

  • Nuchal Translucency (NT) Measurement: This ultrasound test, performed around 11-14 weeks, measures the thickness at the back of the baby’s neck. Increased thickness may indicate a higher risk of Down syndrome. However, for more accurate results, NT is usually combined with other test results.

  • Diagnostic Tests: Chorionic villus sampling (CVS) and amniocentesis are more definitive but invasive. They analyze samples from the placenta or amniotic fluid to examine the baby’s chromosomes directly.

While NIPT offers a high accuracy rate and is less invasive, it may not be universally available through the NHS and might depend on individual circumstances. Combined screening, the quadruple test, and NT measurements offer risk estimates without the risks of invasive procedures. CVS and amniocentesis provide conclusive results but come with a small miscarriage risk.

It’s a deeply personal decision to choose the right screening test for you and your baby. You have various options available to explore further. You can browse through different sections on our website or reach out to us via phone, email, or WhatsApp. Alternatively, you can seek guidance from your NHS midwife or GP for advice and assistance.

What are Down syndrome symptoms during pregnancy?

It’s natural for expectant parents to wonder about the health of their unborn child. It’s important to know that during pregnancy, Down syndrome does not typically cause specific symptoms that you can feel or observe. Most pregnancies with fetal anomalies, including those with Down syndrome, progress without any noticeable difference in maternal symptoms.

However, certain indicators can be observed during an ultrasound, which may suggest the possibility of Down syndrome. These Down syndrome signs are called ‘soft markers’ and could include aspects like nuchal translucency thickness or other physical traits. For a detailed exploration of these ultrasound signs, please see the “ULTRASOUND SIGNS OF DOWN SYNDROME DURING PREGNANCY” section on our website.

If you have any concerns or questions about what these ultrasound markers may mean, we encourage you to speak with your healthcare provider or contact us to arrange a fetal scan or consultation.

Every pregnancy carries a chance of Down syndrome. Is it true?

Down syndrome can occur in any pregnancy, regardless of the parents’ age or whether there’s a family history of the condition. While the chance of having a baby with Down syndrome increases with maternal age, particularly for women over 35, it’s important to note that most babies with Down syndrome are born to younger women because they have more pregnancies overall. 

Down syndrome: Is it genetic?

Yes, Down syndrome is related to genetic factors, primarily due to changes in the number or structure of chromosomes. The most common form, known as trisomy 21, occurs when there is an extra copy of chromosome 21. This additional genetic material is present in every cell of the body and is responsible for the characteristic features of Down syndrome.

However, it’s important to note that most cases are not inherited but rather occur due to a spontaneous error during the formation of reproductive cells. This means that the extra genetic material leading to Down syndrome usually arises randomly in the egg or sperm before conception or sometimes just after fertilisation of the ovum, and it is not typically passed down from parents to their children.

In rare instances, approximately 3% to 4% of cases, Down syndrome may be inherited due to a translocation, where an extra piece or an entire extra chromosome 21 attaches to another chromosome. Inherited translocation Down syndrome occurs when one of the parents carries this rearrangement in their genetic makeup, which can increase the risk of having a child with Down syndrome.

Overall, while Down syndrome has a genetic basis, the vast majority of cases occur sporadically and are not inherited from parents.

What is Down syndrome inheritance?

Understanding Down Syndrome Inheritance: A Genetic Overview

Down syndrome usually isn’t inherited in the typical sense. Instead, it often occurs due to a random error in cell division, resulting in an extra copy of chromosome 21. This extra genetic material leads to the developmental changes and physical features characteristic of Down syndrome.

Types of Down Syndrome:

  1. Trisomy 21 (nondisjunction): This is the most common type, making up about 95% of Down syndrome cases. It happens when a person has three copies of chromosome 21 instead of the usual two. This extra chromosome generally results from a random error in cell division called nondisjunction. Nondisjunction can happen in the mother’s egg, father’s sperm, or shortly after fertilization in the developing embryo.

  2. Mosaic Down Syndrome: In this rarer form, only some of the person’s cells have the extra chromosome 21. This variation results from nondisjunction occurring in one of the early cell divisions after fertilization. Individuals with mosaic Down syndrome might have milder features because some cells have the typical chromosome count.

  3. Translocation Down Syndrome: Accounting for about 3-4% of cases, this type can have a hereditary component. Translocation happens when part of chromosome 21 breaks off during cell division and attaches to another chromosome, often chromosome 14. Parents with this rearranged chromosome may pass it to their children, increasing their risk of Down syndrome.

Inheritance and Risk Factors: While translocation Down syndrome can be inherited, the majority of Down syndrome cases result from random events and are not passed from one generation to the next. Parents of a child with Down syndrome, due to nondisjunction or mosaicism, usually have typical chromosomes. However, the risk of having a child with Down syndrome increases with maternal age, particularly for women over 35.

Chance of Down syndrome by age: Brief explanation

Understanding the Impact of Maternal Age on Down Syndrome Chances:

Becoming a mother at an older age brings many joys along with a few increased risks. One such risk is the likelihood of having a baby with Down syndrome, which gently rises as women get older. This is because the eggs in a woman’s body are more likely to experience chromosomal mishaps as they age, potentially leading to an extra chromosome 21 – the cause of Down syndrome.

After the age of 35, this chance becomes more pronounced. Yet, historically, most babies with Down syndrome were born to younger mothers due to higher birth rates in this age group. With more women choosing to start families later in life, we’re seeing a shift. As of 2021, the average age of new mothers in England and Wales rose to nearly 31 years. This means that more pregnancies are occurring at ages where the risk of Down syndrome is naturally higher.

To put it into perspective, according to a recent report, mothers over 40 have a seven times higher chance of having a baby with genetic conditions like Down syndrome than those under 20.

The likelihood of having a baby with Down syndrome for a 40-year-old mother can also vary at different pregnancy stages:

  • At 10 weeks gestation: about 1 in 60
  • At 16 weeks gestation: about 1 in 75
  • At delivery: about 1 in 100

The changing statistics through gestation reflect the sad reality that some pregnancies with Down syndrome do not go to term. Also, as pregnancy progresses, the mother naturally ages, subtly shifting the probabilities.

Navigating the complex feelings and decisions around this information can be challenging. We invite you to reach out for support and resources tailored to your needs and those of your growing family.

Down syndrome severity spectrum

The severity spectrum of Down syndrome can widely differ among individuals. In terms of intellectual disabilities and physical challenges, the range spans from mild to moderate.

Regarding intellectual disabilities, individuals with Down syndrome commonly experience cognitive delays. Some may have mild impairments, allowing them to acquire basic literacy and functional language skills. However, others might face more significant challenges in learning and communication.

Physically, Down syndrome also presents a diverse spectrum. While some individuals may encounter fewer physical complications and lead relatively healthy lives, others might confront more pronounced health issues. Common physical problems include congenital heart defects, gastrointestinal complications, vision or hearing impairments, and musculoskeletal issues. These concerns can vary in severity from mild to severe and may necessitate medical intervention or therapeutic support.

It’s essential to recognize that each person with Down syndrome is unique, with different levels of intellectual and physical challenges. Early intervention, appropriate healthcare services, and educational support play crucial roles in their development and overall well-being.

What is the connection between Down syndrome and the heart?

Understanding the Heart Health of Babies with Down Syndrome

It’s important for expectant parents to be aware that around half of the newborns with Down syndrome also have congenital heart disease (CHD). This condition can significantly affect their well-being, and being informed is a crucial step in providing the best care.

Individuals with Down syndrome are at a considerably higher risk of heart issues — they are 40 to 50 times more likely to have CHD compared to the general population.

The most common heart defects linked with Down syndrome include atrioventricular septal defect (AVSD), affecting about 45%, and ventricular septal defect (VSD), seen in approximately 30% of heart defect cases. Moreover, in about 25% of babies with Down syndrome, more than one cardiovascular anomaly is present.

Given this strong association between Down syndrome and heart defects, we advise conducting a specialised heart examination known as fetal echocardiography (or fetal echo) at the earliest opportunity in all pregnancies where Down syndrome is suspected or confirmed. Early detection of heart conditions can lead to timely interventions and better long-term outcomes for the child.

At London Pregnancy Clinic, we are proud to offer advanced antenatal care services, including the capability to perform early fetal echocardiography from as early as 12 weeks into the pregnancy. This early examination of your baby’s heart is a crucial step in prenatal health, allowing for the earliest possible detection of heart conditions.

Fetal echocardiography at this stage is particularly beneficial for pregnancies with an increased risk of congenital heart defects, such as those with a diagnosis or suspicion of Down syndrome. By conducting these detailed heart scans, we can identify potential issues much earlier than standard prenatal screening methods, enabling prompt and proactive care.

Our state-of-the-art equipment and experienced specialists ensure the most precise and comprehensive assessment of the fetal heart. This early scan can provide invaluable peace of mind for expectant parents, knowing that any potential heart-related issues can be identified and managed as soon as possible.

We understand that the prospect of any prenatal testing can be daunting. Our team at London Pregnancy Clinic is committed to providing not only the highest standard of medical care but also the emotional support and guidance you need during this journey. We’re here to answer all your questions and ensure you feel comfortable and informed every step of the way.

For more information about early fetal echocardiography and other antenatal services, please contact us. We’re here to support you and your baby with the best care possible from the very start.

What are the reasons behind the false-negative results in NIPT?

False-negative NIPT results for Down syndrome are uncommon. It happens in about 1.4% of all cases of Down’s syndrome.

There are a few biological causes of the false negative NIPT results:

  • Mosaic Down syndrome: When the extra chromosome 21 is present in only some cells, it might not be adequately represented in the cell-free DNA sample taken for the test.
  • Translocation Down Syndrome: NIPT might not reliably detect cases of Down syndrome caused by certain translocation chromosomal rearrangements, such as the 21q;21q rearrangement.
  • Rare Genetic Variants: Uncommon genetic variations or anomalies related to Down syndrome especially isochromosome 21q might not be adequately captured by the NIPT methodology, leading to false-negative results.

Other false-negative causes include:

  • Low Fetal Fraction: Insufficient fetal DNA in the maternal blood sample can lead to inaccurate results, especially in early stages of pregnancy (before 10 weeks).
  • Technical Limitations: Issues during sample collection, processing, or analysis of the cell-free DNA might result in false-negative outcomes.
  • Pregnancy Complications: Maternal health conditions or pregnancy complexities can impact the accuracy of NIPT results.

Undiagnosed mosaic Down syndrome or other situations with false-negative results might lead to the birth of a baby with Down syndrome. To lower this probability, we highly advise undergoing NIPT along with our specialized ultrasound for evaluating the baby’s structures. These scans can be conducted as early as 10 weeks. While a normal structural appearance isn’t conclusive, it decreases the likelihood of delivering a baby with undetected Down syndrome.

4d ultrasound for Down syndrome. Does it help?

The True Utility of 4D Ultrasound in Detecting Down Syndrome.

At London Pregnancy Clinic, we are at the forefront of medical 3D and 4D imaging within London, utilising the most sophisticated Voluson Expert 22 and Voluson E10 scanners that offer unparalleled 3D capabilities. Despite this, we maintain that the significance of 4D scans in diagnosing Down syndrome has been substantially overstated, often by non-medical ultrasound clinics that offer keepsake services not provided by the NHS.

We stand by the conviction that an expert assessment for Down syndrome should be conducted using high-resolution 2D ultrasounds, like those performed with our state-of-the-art scanners. 2D imaging remains the cornerstone of expert fetal scanning, delivering all necessary clinical details regarding the baby’s health, particularly concerning the condition of the heart and brain.

Our Director, Dr Fred Ushakov, possesses a wealth of experience in conducting scans for babies with Down syndrome, including using 3D and 4D imaging techniques. However, in his professional view, even the highest-quality 4D ultrasound cannot definitively detect the facial features associated with Down syndrome that become apparent after birth. More reliable tests, such as NIPT or invasive diagnostic procedures, should be pursued for accurate screening or diagnosis of Down syndrome.

I have fetus with Down syndrome. Can I have 4D scan?

Supportive 3D/4D Ultrasound Services for Expecting Parents at London Pregnancy Clinic

We at London Pregnancy Clinic understand and respect the decisions of prospective parents who choose to continue pregnancies with babies diagnosed with Down syndrome. We recognize your desire to learn more about your baby, including their appearance. To support you, our clinic offers specialized 3D and 4D ultrasound scans, enabling you to visualize your baby’s facial features in detail.

We encourage you to book your scan with Dr Fred Ushakov, an expert in 3D ultrasound imaging renowned for his skill and experience. To achieve the best possible imaging results, we recommend scheduling the scan between 24 and 30 weeks of pregnancy. During this period, technical factors are most favourable for successful 3D imaging.

It’s important to note that our primary focus during the scan is to evaluate the structural integrity and overall well-being of the fetus rather than solely capturing 3D images. We strive to provide the highest quality imaging; however, in some instances, obtaining a clear image might be challenging due to the baby’s position in the womb. Rest assured, our team will make every effort to achieve the best possible results, prioritizing the health and safety of your baby.

At London Pregnancy Clinic, we are committed to offering compassionate care and comprehensive ultrasound services to all expecting parents.

How helpful is Down syndrome 15 week 3d ultrasound?

Understanding the efficacy of a 15-week 3D ultrasound for assessing Down syndrome-related concerns can be confusing for many parents. There’s a common misconception that a 3D scan at 15 weeks provides superior insights compared to a regular 2D scan. However, the critical elements for effective Down syndrome-related scanning involve cutting-edge 2D ultrasound technology and the expertise of the operator.

At our clinic, we specialize in expert 1st-trimester and early 2nd-trimester Down syndrome-related scans. While we utilize 3D and 4D ultrasound technology to augment our clinical scanning capabilities, we firmly believe that the optimal time for assessing Down syndrome-related issues is at 13 weeks rather than 15 weeks. There are several compelling reasons behind our advocacy for earlier scans at 13 weeks:

Firstly, at 13 weeks, there’s the opportunity for accurate NT measurements, crucial for assessing the risk of Down syndrome. Additionally, an early fetal echocardiography performed via transvaginal specialist examination can provide detailed insights into fetal heart health. Furthermore, the ability to conduct fetal brain examination through 3D neurosonography offers additional advantages at this early stage.

Considering these advantages, we strongly recommend an early fetal scan at 13 weeks, accompanied by early fetal echocardiography and clinical 3D ultrasound for all cases related to Down syndrome concerns.

Can ultrasound detect Down syndrome facial features?

Common facial characteristics associated with Down syndrome are:

  • Flattened facial profile, particularly the bridge of the nose
  • Almond-shaped eyes with an upward slant
  • Shorter neck
  • Small ears
  • Protruding or enlarged tongue

Speckled spots in the iris (coloured part) of the eye, known as Brushfield spots

Understanding the Limitations and Uses of 4D Ultrasound in Down Syndrome Assessments

4D ultrasound technology has the remarkable ability to produce vivid images of a baby’s face, capturing even facial expressions and perceived emotions. However, it’s important to understand its limitations, especially when it comes to detecting Down syndrome-related facial characteristics. Despite the advanced capabilities of 4D scanning, many features indicative of Down syndrome might not be identifiable through ultrasound.

One challenge with 4D imaging is its dependence on the baby’s position during the scan. If the baby is facing away, obscured by their own limbs, or the umbilical cord is in the way, the clarity of the images can be significantly affected. In some cases, 3D and 4D imaging may be suboptimal or provide limited information.

That said, there are specific facial markers linked to Down syndrome that can be observed through ultrasound. The most notable among these are:

  • An absent or underdeveloped nasal bone (NB)
  • Prenasal thickness or nose skin oedema (swelling)
  • Enlarged tongue

At London Pregnancy Clinic, we pay close attention to these facial features during Down syndrome-related scans. We utilise 3D ultrasound technology whenever possible to comprehensively assess the fetal face. While 3D and 4D ultrasounds offer valuable insights, we always consider the full spectrum of available markers to provide the most accurate assessment for expectant parents.

Our commitment is to offer you detailed, compassionate care using the best available technology to ensure you receive the most thorough and informative prenatal screening experience.

Down syndrome tongue. What is macroglossia?

In individuals with Down syndrome, macroglossia, or an enlarged tongue, is a relatively common physical characteristic. This enlarged tongue might appear larger in proportion to the mouth, leading to potential difficulties with speech, swallowing, or fitting comfortably within the oral cavity. It’s among the notable physical features observed in babies and individuals with Down syndrome, contributing to distinct facial characteristics often associated with the condition.

In prenatal ultrasound, macroglossia might be identified by observing a disproportionately larger tongue within the fetal mouth cavity compared to what is typically expected at that stage of development. This enlargement can sometimes be noticed as a protrusion or a relatively significant space occupation within the oral cavity during ultrasound examinations. However, diagnosing macroglossia solely through ultrasound might be challenging, as it often necessitates confirmation postnatally through a physical examination after birth.

Some medical experts consider macroglossia as a potential soft marker for Down syndrome during prenatal assessments. However, interpreting this finding solely based on prenatal observations can be challenging. This is because in-utero activities like sucking or yawning might cause normal babies to protrude their tongues, leading to a misinterpretation of macroglossia.

Moreover, it’s important to note that macroglossia can be linked to various genetic syndromes other than Down syndrome. For instance, it is notably associated with Beckwith-Wiedemann syndrome, which is a different genetic condition characterized by overgrowth, abdominal wall defects, and an increased risk of certain childhood tumors. Therefore, while macroglossia might be observed as a potential marker, its interpretation in prenatal evaluations needs to be done cautiously, considering its association with other syndromes apart from Down syndrome.

I had low risk Down syndrome but still worried. What can I do?

Understanding and Managing Concerns About Down Syndrome Screening Results.

We recognize that receiving a low-risk result for Down syndrome can still be a source of worry for some parents. For example, if you had a chance of Down syndrome of 1 in 10,000 in a previous pregnancy and now face a 1 in 5,000 chance, this change might feel alarming. It’s important to understand that such variations are often due to natural factors, like a slight increase in maternal age, rather than a significant change in actual risk.

We also understand the concerns about the accuracy of combined screening tests (CST). While CST is a widely used method, it’s not flawless. Challenges in measuring the nuchal translucency (NT) during ultrasound can lead to worries about false-negative results. While CST is generally reliable, research indicates that it might not detect Down syndrome in about 1 out of every 5 cases. This statistic is meant to provide a realistic perspective, not to alarm you, but to inform you about the screening’s limitations.

To offer peace of mind, we recommend considering Non-Invasive Prenatal Testing (NIPT). NIPT is renowned for its accuracy in detecting Down syndrome, backed by numerous studies. It provides more definitive results, reducing the uncertainty that can come with standard screenings.

At our clinic, we take extra care by conducting NIPT only after a detailed structural examination of the baby by an advanced ultrasound scan. This comprehensive approach ensures that we consider all aspects of your baby’s health, providing you with the most accurate and reassuring information possible.

Can ultrasound predict Down syndrome severity?

Ultrasound scans during pregnancy help observe the baby’s development and may detect certain physical features associated with Down syndrome. However, it’s crucial for parents to understand that there’s no established link between ultrasound findings and the severity of intellectual disabilities in Down syndrome.

There isn’t concrete scientific evidence suggesting a direct correlation between what’s observed on ultrasounds and the level of intellectual challenges the child might face. While ultrasound may identify certain physical conditions linked to Down syndrome, like heart defects, it doesn’t provide insight into the extent of intellectual disabilities.

From an empirical standpoint, when ultrasound shows multiple severe physical features associated with Down syndrome, some may infer that the baby could face more significant challenges. However, this assumption isn’t guaranteed. Intellectual disability severity in Down syndrome varies widely among individuals, and no direct connection has been established between ultrasound findings and the extent of these challenges.

It’s important to approach ultrasound results cautiously and not solely rely on them to predict the severity of intellectual disabilities. Instead, consultations with healthcare providers, early interventions, and ongoing support post-birth are vital in understanding and addressing the specific needs of a child with Down syndrome.

How do the physical features observed in fetuses with Down syndrome during ultrasound differ from those seen in children after birth?

The physical features of fetuses with Down syndrome observed through ultrasound can be notably different from the features seen in children after birth. This discrepancy isn’t due to structural anomalies like atrioventricular septal defects (AVSD) or duodenal atresia, which remain consistent between ultrasound observations and after birth.

Structural anomalies such as AVSD or duodenal atresia typically show distinct abnormalities that are consistently identified both during prenatal ultrasound examinations and upon the child’s birth. However, the facial characteristics associated with Down syndrome observed through ultrasound can appear less pronounced or different in the womb compared to how they manifest in children after birth. This difference is due to the ongoing development and maturation of facial features after the ultrasound stage and doesn’t signify a structural anomaly change.

Can 13 week ultrasound exclude Down syndrome?

The 13-week ultrasound serves as an effective tool to rule out approximately 50% of fetal structural anomalies. Our Early Fetal Scan is specially designed for this purpose. However, it’s important to note that while ultrasound can detect structural issues like heart defects or markers associated with Down syndrome, it doesn’t directly check for Down syndrome.

We recommend Non-Invasive Prenatal Testing (NIPT) as our preferred screening method for Down syndrome, primarily due to its outstandingly high ability to accurately rule out the condition. Ideally, NIPT is performed at 10 weeks of pregnancy, but if this window has passed and you’re currently at 13 weeks, it’s not too late to undergo NIPT. Feel free to contact us for further guidance and advice.

Blood test for Down syndrome: explanation

The blood tests used for Down syndrome screening fall into two categories. The first type of test, part of the combined test and quadruple test (Quad test), examines surrogate biochemical markers—specifically PAPP-A (Pregnancy-associated plasma protein-A) and HCG (human Chorionic Gonadotropin). However, it’s important to note that these tests have a notable rate of both false positives and false negatives.

The combined test evaluates these markers alongside ultrasound findings to estimate the risk of Down syndrome. Similarly, the Quad test, performed later in pregnancy, also assesses these markers and other biochemical parameters but solely via blood analysis. NHS screening program uses one of those tests to screen for chromosomal anomalies.

The newest blood test for Down syndrome is the NIPT (Non-Invasive Prenatal Testing), which relies on fetal cell-free DNA (cfDNA) circulating in the mother’s blood. NIPT is notably more accurate compared to the biochemical marker-based tests. It examines fetal genetic material and demonstrates higher precision in detecting chromosomal abnormalities, including Down syndrome, with a reduced rate of false positives and false negatives.

Down syndrome blood test results explained

In the combined screening test, an elevated risk for Down syndrome is linked to lower PAPP-A levels and higher HCG levels. Both these biochemical markers are measured in MoMs (Multiples of Median) and the greater the difference in MoMs, the higher the likelihood of Down syndrome. These values are assessed alongside NT (nuchal translucency) measurements, and the collective result provides a probability of Down syndrome, often expressed as odds such as 1 in a particular number. In the NHS, probabilities of 1 in 150 or greater are considered indicative of a heightened likelihood of Down syndrome.

At the London Pregnancy Clinic, we opt not to utilize the combined screening test due to its reduced sensitivity and potential for false-negative outcomes. Instead, we prioritize the use of NIPT (Non-Invasive Prenatal Testing). This advanced screening method involves analyzing fetal cell-free DNA present in the mother’s bloodstream, providing a more accurate assessment for various chromosomal abnormalities, including Down syndrome. NIPT significantly enhances our ability to detect these conditions, contributing to a more reliable and precise screening process for our patients.

How are low PAPP-A levels associated with Down syndrome?

Low levels of PAPP-A (Pregnancy-associated plasma protein-A) in the first trimester of pregnancy can sometimes indicate an increased risk of specific chromosomal abnormalities, including Down syndrome. PAPP-A, a protein produced by the placenta, is routinely measured during initial pregnancy screenings at 11-13 weeks.

When PAPP-A levels are unusually low, along with other markers like increased nuchal translucency (NT) and abnormal levels of human chorionic gonadotropin (hCG), it may contribute to a higher chance for Down syndrome. However, it’s crucial to note that low PAPP-A alone does not conclusively indicate Down syndrome. It’s among several factors considered in combined screening tests (which involve ultrasound and blood tests) to evaluate the likelihood of chromosomal abnormalities in the fetus.

If low PAPP-A levels are detected during pregnancy, healthcare professionals might recommend further testing, such as non-invasive prenatal testing (NIPT) or invasive procedures like chorionic villus sampling (CVS) or amniocentesis, to provide a more precise diagnosis regarding the presence of Down syndrome or other chromosomal conditions.

What does mosaic Down syndrome (mosaic trisomy 21) mean?

Mosaic Down Syndrome During Pregnancy: Understanding Its Variations.

Mosaic Down syndrome, a less common form of Down syndrome, occurs in about 1-2% of all trisomy 21 cases. Unlike typical Down syndrome, where each cell of the baby has an extra chromosome 21, mosaic Down syndrome presents a mix – some cells have the extra chromosome, while others don’t. This happens due to a cell division error in early fetal and/or placental development, leading to a mix of cells, some with and some without the extra chromosome.

Types of Mosaicism During Pregnancy:
During pregnancy, mosaicism can manifest differently compared to after birth. Abnormal cells may be present in the baby, the placenta, or both. The types range from confined placental mosaicism to true fetal mosaicism.

  • In confined placental mosaicism, only the placenta has trisomy 21, leaving the baby unaffected. Fortunately, this condition is more common prenatally than true fetal mosaicism. This type of mosaicism can cause false positive results of NIPT.
  • In true fetal mosaicism, the number of cells with the extra chromosome varies among babies, affecting the severity of symptoms. These can range from mild to moderate intellectual disabilities and physical symptoms typical of Down syndrome, like distinct facial features and possible health issues, including heart defects.

The presence and quantity of the extra chromosome in true fetal mosaic Down syndrome can lead to a wide range of symptoms and severity, and each case is unique. The extent of the condition can vary greatly, making personalized care and monitoring essential.

High mosaic and low mosaic Down syndrome, what does it mean?

Mosaic Down syndrome characteristics vary significantly from person to person, influenced by the number of cells with the extra chromosome.

Mosaic Down syndrome is a distinct variant of Down syndrome, marked by the fact that not all cells in an individual’s body carry the additional chromosome 21, which is typically associated with Down syndrome. In cases described as “high mosaic,” a larger proportion of cells contain this extra chromosome, while “low mosaic” refers to scenarios where fewer cells are affected.

This variation in the number of affected cells leads to a broad spectrum of Down syndrome characteristics. Generally, the more cells with the extra chromosome, the more pronounced the Down syndrome features tend to be. Conversely, individuals with lower levels of mosaicism often experience milder symptoms or fewer Down syndrome traits. It’s crucial to understand, however, that the correlation between the degree of mosaicism and the severity of symptoms is not consistent across all cases.

Mosaic Down syndrome symptoms. Are they different?

Mosaic Down Syndrome Physical Characteristics

Mosaic Down syndrome is a unique form of Down syndrome where symptoms can vary significantly. This variation is mainly due to the proportion of cells in the body that carry the extra chromosome 21. Unlike typical Down syndrome, children with mosaic Down syndrome may exhibit milder common features.

Physical characteristics and facial features of mosaic Down syndrome: Often, these children may have typical Down syndrome features like almond-shaped eyes or a flat profile, but less pronounced. This milder manifestation of physical characteristics and facial features makes mosaic Down syndrome distinct.

Despite the challenges in predicting specific symptoms or their severity due to cell variability, recognizing these mosaic Down syndrome physical characteristics can aid early diagnosis and intervention.

Emerging research has shown that individuals with low-level mosaic trisomy 21 often experience more favourable developmental and intellectual outcomes than those with higher mosaicism levels. Detecting low-level mosaic trisomy 21, especially during prenatal tests like amniocentesis, is linked to milder clinical manifestations and improved developmental outcomes in childhood.

However, it’s crucial to understand that the correlation between the level of mosaicism and pediatric outcomes is still a subject of ongoing research. While a more favourable prognosis is often observed in low-level mosaic cases, individual conditions can vary widely. Each child’s experience with mosaic Down syndrome is unique, and outcomes can differ based on various factors.

What does mild or minor Down syndrome mean?

The term “minor Down syndrome” or “mild Down syndrome” isn’t commonly used within medical contexts. Down syndrome, irrespective of its presentation, encompasses a wide range of variations in intellectual and physical characteristics among individuals.

Mosaic Down syndrome, a less common form of the condition, occurs when some cells in the body have an extra copy of chromosome 21, while others have the typical two copies. This mosaic pattern results in varying degrees of impact on an individual’s development and functioning. The severity of symptoms in mosaic Down syndrome can vary widely, leading to a spectrum of challenges that may range from mild to moderate.

However, the term “minor” or “mild” Down syndrome doesn’t specifically denote a separate category within the condition. Instead, it’s more common to describe individuals based on the variation or mosaic nature of their Down syndrome, recognizing the diversity in their abilities and challenges.

In essence, mosaic Down syndrome encompasses a range of outcomes, and the severity can vary significantly among affected individuals. Each person’s experience with mosaic Down syndrome is unique, with a combination of intellectual, physical, and developmental characteristics that may be mild or more moderate in nature.

Can mosaic trisomy 21 lead to false positive NIPT?

Certainly, mosaic trisomy 21 can contribute to a false-positive result in NIPT. This occurs when the additional chromosome 21 is present solely in placental cells but not in the cells of the developing fetus. This situation is termed confined placental mosaicism.

Confined placental mosaicism emerges when abnormal cells with an extra chromosome 21 are identified in the placenta, while the cells within the fetus maintain a normal chromosomal count. The placenta originates from distinct cells compared to those forming the baby, occasionally leading to genetic variations specifically in the placental tissue, not affecting the genetic makeup of the developing baby.

NIPT analyzes cell-free DNA from the placental external layer, known as syncytiotrophoblast, rather than the fetal DNA directly. The term “cell-free fetal DNA” is a simplification used to explain how NIPT works.

In cases where mosaic trisomy 21 is confined to the placenta, the unaffected fetal cells maintain a standard chromosomal count. As NIPT primarily detects placental cells, the presence of abnormal cells in the placenta could lead to a positive NIPT result for trisomy 21, despite the fetus itself not having the extra chromosome 21.

The Role of Expert Ultrasound (Early Fetal Echocardiography):

When NIPT suggests a high chance of trisomy 21, but subsequent ultrasounds show normal fetal development, it could indicate confined placental mosaicism. An expert ultrasound, focusing on critical developmental markers like heart structure, becomes vital in such cases.

When the expert ultrasound reveals normal fetal development and no notable heart defects, this situation can suggest the possibility of confined placental mosaicism. In such cases, it’s essential to have an informed discussion about the next steps in prenatal testing.

This discussion typically revolves around choosing between chorionic villus sampling (CVS) and amniocentesis. Both procedures offer valuable insights but differ in their approach and timing.

Chorionic villus sampling (CVS) can be conducted earlier (at 11-13 weeks), but since CVS assesses placental genetics, in the case of confined placental mosaicism it might not give a complete picture of the baby’s chromosomal makeup.

Amniocentesis, typically performed from 15-16 weeks of pregnancy, is often suggested in these cases to confirm the baby’s chromosomal status. Amniocentesis provides a more accurate assessment of the fetal genetic condition compared to CVS.

For parents facing a high-chance NIPT result for trisomy 21, discussions with healthcare professionals are crucial. They can guide you through the implications of the NIPT results and the subsequent steps, including detailed ultrasounds and possibly CVS or amniocentesis, to ensure a comprehensive understanding of your baby’s health.

If the baby’s NIPT results indicate a high chance of trisomy 21, but the ultrasound shows no signs of this condition, we offer early fetal echocardiography as a next step. This detailed heart scan helps confirm the normal development of the heart and other fetal structures, as well as the absence of additional markers associated with Down syndrome.

Gathering this information is crucial in guiding your next decisions. It gives you and your healthcare providers a clearer picture, helping you determine whether to proceed with Chorionic Villus Sampling (CVS) immediately or to delay the invasive test. If you choose to wait, amniocentesis can be performed after 15-16 weeks of pregnancy, offering more definitive insights into your baby’s chromosomal status.

Can mosaic Down syndrome result in false negative NIPT?

Mosaic Down syndrome can lead to inaccurate results in NIPT, potentially causing a diagnostic failure. Fortunately, cases of false negative NIPT results due to true fetal mosaic Down syndrome are uncommon. However, it’s important to be aware that they can occur.

NIPT, which analyzes cell-free DNA in the mother’s bloodstream, primarily reflects the genetic makeup of the placenta rather than the fetus. In instances of mosaic Down syndrome, where the distribution of the extra chromosome 21 varies among cells, NIPT may not detect this variation, leading to a false negative result.

The Role of Ultrasound and Further Diagnostic Tests:

A detailed ultrasound scan combined with NIPT plays a crucial role in avoiding these situations. If the scan is normal, particularly with a well-formed heart, it significantly reduces the chances of undetected true fetal trisomy 21 mosaic. The expert ultrasound assessment of fetal development, especially the heart, provides valuable reassurance about the likelihood of chromosomal abnormalities in the context of low-chance NIPT results.

However, if a baby with a low-chance NIPT result exhibits multiple ultrasound markers of Down syndrome, particularly heart defects, further diagnostic testing may be necessary. In such cases, procedures like chorionic villus sampling (CVS) or amniocentesis are recommended.

These tests provide a definitive assessment of the baby’s chromosomal status, helping to confirm or rule out the presence of Down syndrome, especially in cases where ultrasound findings raise concerns.

Translocation Down syndrome

Translocation Down syndrome, a less common form of Down syndrome, represents 3% to 4% of all Down syndrome cases and arises when a part of chromosome 21 attaches itself to another chromosome. In some cases, a parent who doesn’t have Down syndrome may carry this translocation in a balanced form, where the genetic material is present in the right amount but arranged incorrectly.

When this translocation is passed to their child, it might result in an unbalanced form, causing the baby to have an excess or shortage of genetic material. Notably, this form of Down syndrome holds a significant recurrence risk in future pregnancies, prompting families in this situation to be offered genetic counselling.

Translocation Down syndrome cases involve an unbalanced translocation between chromosome 21 and another acrocentric chromosome (chromosome with a very tiny short arm), commonly chromosome 14, known as the Robertsonian translocation. Roughly 75% of translocations occur spontaneously (de novo), while 25% are inherited from a parent carrying this translocation.

Translocation Down syndrome looks the same as regular trisomy 21 syndrome. Despite the genetic variation, babies with translocation Down syndrome experience similar health challenges and learning difficulties seen in other types of Down syndrome.

The risk of Down syndrome recurrence depends on the karyotype of the parents. If both parents have normal chromosomes, the chance of it happening again is approximately 2% to 3%.

When one parent has a Robertsonian translocation, the chances of it happening again depend on the parent’s gender and the specific chromosome involved in the translocation. If it’s the mother with the translocation, the risk is about 10% to 15%. If it’s the father, the risk is less, usually less than 5%.

But, if one parent has a 21:21 translocation, the risk of it happening again is nearly 100%. These are just estimates, though. When translocation Down syndrome is found, it’s crucial for the parents to talk to a genetics expert and get their own chromosomes checked (a karyotype) to know if they also have this type of translocation or not. This helps to understand the chances of it happening again in future pregnancies.

Can NIPT detect translocation trisomy 21?

NIPT (Non-Invasive Prenatal Testing) primarily screens for common chromosomal abnormalities, such as trisomy 21 (Down syndrome), by detecting extra fetal cfDNA related to chromosome 21. There are two separate issues regarding NIPT and translocation Down syndrome:

  1. False-negative NIPT results: In 2-4% of Down syndrome cases, a Robertsonian translocation might be the cause. Theoretically, NIPT is designed to assess the risk based on the presence of an additional copy of chromosome 21, regardless of whether it’s due to a Robertsonian translocation or free trisomy. In actual practice, when examining the false-negative outcomes of the NIPT, over 25% of these cases were associated with translocation Down syndrome. This finding indicates that the infrequent translocation variant of Down syndrome increases the likelihood of false negatives in NIPT results. To minimize false negatives, it’s recommended to complement NIPT with advanced ultrasound examinations before the blood test, starting from the 10th week of pregnancy (10 Week Scan or Early Fetal Scan). A normal detailed fetal examination can further reduce the chances of false negative NIPT results.
  2. Risk of Down syndrome recurrence in subsequent pregnancies: NIPT might not specifically identify the type of trisomy or detect the specific genetic rearrangements linked with translocation Down syndrome. For a thorough assessment or exclusion of translocation Down syndrome, additional tests like chromosomal microarray analysis (CMA) or karyotyping are usually suggested. Although invasive, these tests offer more detailed insights into chromosomal structure, identify translocations, and assess the risk of recurrence in future pregnancies.
My baby has Down syndrome at 13 week. How can I check its heart?

Support and Care Following a Down Syndrome Diagnosis at London Pregnancy Clinic.

Receiving a confirmed diagnosis of Down syndrome through procedures like Chorionic Villus Sampling (CVS) or amniocentesis can be a challenging moment for any family. At London Pregnancy Clinic, we are committed to providing comprehensive support and care during these times, especially when it comes to understanding your baby’s health in greater detail.

To aid parents in making informed decisions about their pregnancy, we offer early fetal echocardiography as soon as 12 weeks. This early heart scan is crucial for assessing the baby’s cardiac health, giving you essential information that can be vital in guiding your choices. Our approach is thorough and sensitive, typically combining both transabdominal and transvaginal methods to ensure we leave no stone unturned in evaluating your baby’s heart.

Research has shown that early fetal echocardiography can identify up to 80% of severe cardiac anomalies that are detectable before birth. This level of early detection is crucial, as it allows for better planning and preparation for any necessary medical interventions after birth.

We understand the emotional complexities involved in continuing a pregnancy after a Down syndrome diagnosis. Our team is here not just to provide medical expertise but also to offer emotional support and understanding. We believe in empowering you with as much information as possible about your baby’s condition so that you can make decisions that are right for you and your family.

If you find yourself facing such a diagnosis, please know that you are not alone. The London Pregnancy Clinic is here to support you with compassion, care, and the highest standard of medical expertise.

Dr John Langdon Down and “Mongolism syndrome”

Dr John Langdon Down, an English physician, described a condition in the late 1866s that later became known as “Down syndrome”. In his original descriptions, Dr Down used the terms “Mongol” or “Mongolian type” to refer to this condition. This terminology, “Mongol Child”, “Mongolism syndrome,” or “Mongoloid”, was widely used in medical literature and beyond as a descriptor for individuals with Down syndrome.

However, as societal understanding progressed and the scientific community became more aware of the derogatory nature of using ethnic terms to describe medical conditions, the term “Mongolism syndrome” began to be seen as inappropriate and offensive. This term suggested an erroneous connection between the condition and the Mongolian ethnicity, which was both inaccurate and culturally insensitive.

By the 1970s, as awareness of the implications of such terminology grew, there was a concerted effort within the medical community to abandon the term “Mongol” or “Mongolism” in describing Down syndrome. This shift aimed to eliminate the use of racially charged or inappropriate language in the medical field, recognizing the importance of respectful and accurate language in referring to individuals with disabilities.

Subsequently, the term “Down syndrome” became the widely accepted and preferred term to describe this chromosomal condition, honouring Dr Down’s pioneering observations while discarding the outdated and offensive terminology.

What is the current Down syndrome life expectancy?

As of now, the life expectancy for individuals with Down syndrome has notably increased due to advancements in medical care and treatments. With the availability of cardiac surgeries, vaccinations, antibiotics, thyroid hormone treatments, leukaemia therapies, and anticonvulsant drugs, the quality of life and life expectancy for people with Down syndrome have significantly improved.

On average, individuals with Down syndrome can now expect to live into their 60s, with some reaching even older ages. However, life expectancy can vary based on various factors, including the presence of associated health conditions and access to proper healthcare and support.

Who are the oldest people with Down syndrome known in the UK?

In the United Kingdom, several remarkable individuals with Down syndrome have defied the odds by surpassing typical life expectancies and reaching advanced ages. Their longevity has contributed significantly to understanding the potential lifespan and quality of life for people living with Down syndrome.

The best-known old people with Down syndrome in the UK are:

Joe Sanderson from Saltburn, Cleveland, possibly one of the oldest living men with Down’s syndrome, marked his 80th birthday in 2016.

Elizabeth Eastley from Bampton, Devon, celebrated her 77th birthday in 2022.

Kenny Cridge from Yeovil, Somerset, previously recognized by Guinness World Records (2008) as the oldest living man with Down’s Syndrome, turned 76 in 2016.

Frances Gillett from Ely, Cambridgeshire, defied expectations by celebrating her 75th birthday in 2016.

These individuals have demonstrated remarkable longevity and challenging perceptions about the life expectancy of people with Down syndrome.

What are the chances of Down syndrome with no family history?

The vast majority of parents who have babies with Down syndrome do not have any prior family history of the condition. Down syndrome predominantly occurs in pregnancies of healthy mothers and is primarily associated with advancing maternal age. While the risk of having a baby with Down syndrome increases with maternal age, most cases occur in families without any previous history of the condition.

Down syndrome test during pregnancy: Explanation

Your Guide to Down Syndrome Testing During Pregnancy

Expecting a baby is a journey filled with anticipation and, sometimes, a bit of worry. One aspect you might consider is screening for Down syndrome. Here’s a straightforward breakdown of the tests available:

  1. Non-Invasive Prenatal Testing (NIPT) from 10 weeks: This simple blood test looks for tiny pieces of the baby’s DNA circulating in your bloodstream. It’s very reliable and can identify if there’s an increased risk of Down syndrome with minimal chance of getting it wrong.

  2. Combined Screening Test (CST) between 11-14 weeks: This two-step test includes a blood sample (to check PAPP-A and hCG hormone levels) and an ultrasound scan (to measure the nuchal translucency or the fluid at the back of the baby’s neck). Together, these give us a clearer picture of the likelihood of Down syndrome.

  3. Quadruple Test (Quad test) between 14-20 weeks: Another blood test checks four different markers in your blood. It helps us understand if there’s an increased risk of Down syndrome. Unfortunately, this test is not very accurate.

  4. Nuchal Translucency (NT) Thickness Measurement: Done via ultrasound between 11-14 weeks, this measures the skin’s thickness at the back of the baby’s neck. In the UK, this is usually combined with blood markers (CST) for a more accurate assessment.

  5. Diagnostic Tests: For a definite answer, there are tests like Chorionic villus sampling (CVS) from 11-14 weeks and amniocentesis from 15 weeks. These involve sampling the placenta or amniotic fluid to check the baby’s chromosomes directly. They’re more invasive and have a slight risk of miscarriage but can give a conclusive result.

NIPT is a popular choice as it’s highly accurate and less invasive. However, its availability might vary on the NHS. The CST, quadruple test, and NT measurement offer risk estimates rather than a definite diagnosis. If you’re considering these tests, having a conversation with your healthcare provider or our staff is crucial. They can help you weigh the pros and cons and choose the best option for you based on your medical history and personal preferences.

At every step of this journey, we’re here to support and guide you, ensuring you feel informed and reassured about your choices.

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