DiGeorge Syndrome

DiGeorge syndrome is a genetic disorder caused by the deletion of a small piece of chromosome 22, specifically the 22q11.2 region. This chromosomal deletion disrupts the normal development of several body systems during fetal development, leading to a wide range of potential symptoms and complications. The condition is also known as 22q11.2 deletion syndrome, velocardiofacial syndrome, or CATCH-22 syndrome.

The syndrome affects multiple organ systems and can cause congenital heart defects, immune system problems, learning difficulties, and distinctive facial features. The severity and combination of symptoms varies greatly between individuals, with some people having mild symptoms whilst others experience significant medical complications requiring lifelong specialist care.

DiGeorge syndrome is caused by a deletion of genetic material from the long arm of chromosome 22, specifically in the 22q11.2 region. This deletion removes approximately 30-40 genes that are important for normal development of various body systems. The deletion occurs randomly in most cases, though it can be inherited from an affected parent.

In about 90% of cases, the deletion occurs spontaneously with no family history of the condition. In the remaining 10% of cases, the deletion is inherited from a parent who carries the same chromosomal deletion. The deleted genes are crucial for normal development of the heart, immune system, parathyroid glands, and other structures.

DiGeorge syndrome can be detected during pregnancy through several screening and diagnostic approaches. Non-invasive prenatal testing (NIPT) can screen for 22q11.2 deletions from 10 weeks of pregnancy using maternal blood samples. Detailed ultrasound scans may identify structural abnormalities commonly associated with the syndrome, particularly heart defects.

Definitive diagnosis requires genetic testing through amniocentesis or chorionic villus sampling (CVS), which can confirm the presence of the chromosomal deletion with over 99% accuracy. These diagnostic procedures are typically recommended when screening tests suggest increased risk or when characteristic abnormalities are detected on ultrasound examination.

DiGeorge syndrome affects multiple body systems and symptoms can include congenital heart defects (present in about 60-80% of cases), immune system deficiency leading to increased infections, low calcium levels due to parathyroid gland problems, and learning difficulties or developmental delays. Distinctive facial features may include a long face, narrow eyes, and a prominent nose.

Other symptoms can include cleft palate or other feeding difficulties, kidney problems, hearing loss, and behavioural challenges including attention deficit disorders or autism spectrum features. The severity of symptoms varies greatly between individuals, with some experiencing mild symptoms whilst others require extensive medical management throughout life.

DiGeorge syndrome can be inherited, but in most cases (about 90%) it occurs spontaneously without any family history. When one parent has the condition, there is a 50% chance of passing the deletion to each child, as it follows an autosomal dominant inheritance pattern. If neither parent has the syndrome, the risk of having another affected child is less than 1%.

Genetic counselling is recommended for families affected by DiGeorge syndrome to understand inheritance risks and reproductive options. Some affected individuals may not be diagnosed until adulthood or may have very mild symptoms, so family history evaluation should include assessment for subtle signs of the condition in relatives.

Congenital heart defects occur in approximately 60-80% of individuals with DiGeorge syndrome and are often the most serious complications. Common heart problems include tetralogy of Fallot, truncus arteriosus, interrupted aortic arch, and ventricular septal defects. These are complex structural abnormalities affecting the major blood vessels and heart chambers.

Many of these heart defects require surgical correction in infancy or early childhood, and some children may need multiple operations. Fetal echocardiography during pregnancy can identify these cardiac abnormalities, allowing for appropriate preparation and delivery planning at specialist centres with paediatric cardiac surgery capabilities.

DiGeorge syndrome affects immune system development because the deletion includes genes important for thymus development. The thymus is crucial for T-cell production and immune system maturation. Many individuals have reduced T-cell numbers and function, leading to increased susceptibility to infections, particularly viral and fungal infections.

Most people have partial immune deficiency that often improves with age through natural immune system development. However, some individuals may require immunoglobulin replacement therapy, prophylactic antibiotics, or other immune support treatments. Live vaccines may need to be avoided or modified based on individual immune function assessment.

Learning difficulties are common in DiGeorge syndrome, affecting approximately 70-90% of individuals to varying degrees. These may include mild to moderate intellectual disability, specific learning disorders affecting mathematics and reading, and speech and language delays. Many children benefit from early intervention and educational support services.

Behavioural and psychiatric conditions are also more common, including attention deficit hyperactivity disorder (ADHD), autism spectrum disorders, anxiety, and in older individuals, increased risk of schizophrenia and bipolar disorder. Early identification and appropriate support can significantly improve outcomes and quality of life.

Whilst there is no cure for DiGeorge syndrome, many of the associated problems can be treated effectively with appropriate medical management. Heart defects often require surgical correction, immune system problems may need specific treatments or prophylaxis, and low calcium levels can be managed with supplements and medication.

Treatment is tailored to individual symptoms and may involve multiple specialists including cardiologists, immunologists, endocrinologists, and developmental paediatricians. Early intervention services, speech therapy, educational support, and psychological services can significantly improve outcomes and help individuals reach their full potential.

The prognosis for DiGeorge syndrome varies greatly depending on the severity of symptoms, particularly the presence and complexity of heart defects. Many individuals with milder forms of the condition can lead relatively normal lives with appropriate medical management and support. However, those with severe heart defects or significant immune deficiency may face more serious challenges.

With appropriate medical care and support, most children with DiGeorge syndrome can attend mainstream schools and many adults can live independently or semi-independently. Life expectancy depends largely on the severity of heart defects and other medical complications, but many individuals live well into adulthood with good quality of life.

Pregnancies affected by DiGeorge syndrome require specialist monitoring and care planning, particularly when fetal heart defects are identified. Delivery should be planned at a centre with paediatric cardiac surgery capabilities when complex heart defects are present. Some babies may need immediate medical intervention after birth for heart problems or other complications.

Prenatal identification allows for optimal preparation including assembly of appropriate specialist teams, planning for potential neonatal intensive care needs, and psychological support for families. Many babies will need immediate assessment of heart function, immune system, and calcium levels, and may require specialised feeding support if cleft palate or other feeding difficulties are present.

Several screening options are available for DiGeorge syndrome during pregnancy. Non-invasive prenatal testing (NIPT) can screen for 22q11.2 deletions from 10 weeks of pregnancy. NIPT is a screening test, not a diagnostic one, so a high-chance result should be confirmed with diagnostic testing such as CVS or amniocentesis. Detailed ultrasound scans can identify structural abnormalities that may suggest the condition, particularly heart defects and other anatomical features.

Screening is particularly recommended when there is a family history of DiGeorge syndrome, when structural abnormalities are detected on ultrasound, or when other risk factors are present. Comprehensive genetic screening may also be considered for couples planning pregnancy, especially if there are any concerning family history features.

DiGeorge syndrome is one of the most common chromosomal deletion syndromes, though many cases may go undiagnosed due to the variable nature of symptoms. As diagnostic techniques improve and awareness increases, more individuals with milder forms of the condition are being identified.

The syndrome affects all ethnic groups equally and occurs in both males and females with equal frequency. Modern screening methods allow for earlier detection, and genetic counselling can help families understand their risks and reproductive options.

Comprehensive support is available through specialist genetic services, paediatric teams, and dedicated support organisations. Many hospitals have multidisciplinary clinics specifically for DiGeorge syndrome that coordinate care between different specialists and provide ongoing monitoring and support throughout childhood and into adulthood.

Support groups and charities provide valuable resources for families, including information, peer support, and advocacy. Educational support services can help ensure children receive appropriate accommodations and interventions to reach their potential. Genetic counselling services provide ongoing support for family planning and risk assessment for relatives.

Many people with DiGeorge syndrome can have children, though there are important considerations regarding inheritance and pregnancy management. When one parent has the condition, there is a 50% chance of passing the deletion to each child, so genetic counselling is essential for understanding risks and reproductive options.

Preconception planning is important to ensure optimal health before pregnancy and to discuss available screening and diagnostic options. Some couples may consider preimplantation genetic diagnosis (PGD) to reduce the risk of having an affected child, whilst others may choose prenatal testing during pregnancy to inform pregnancy management and preparation.

Regular monitoring throughout childhood is essential for individuals with DiGeorge syndrome to identify and address developing problems early. This includes regular cardiology assessments for heart problems, immunology monitoring for immune function, endocrine monitoring for calcium and hormone levels, and developmental assessments for learning and behavioural needs.

Specialist clinics often coordinate this care to ensure all aspects of the condition are monitored appropriately and that families receive comprehensive support. Regular hearing assessments, dental care, and psychological support may also be needed, with the frequency of monitoring adjusted based on individual needs and symptom severity.

If DiGeorge syndrome is suspected during pregnancy, it’s important to seek specialist genetic counselling and maternal-fetal medicine consultation promptly. This allows for comprehensive risk assessment, discussion of diagnostic testing options, and appropriate pregnancy management planning. Detailed fetal assessment including echocardiography will be important to evaluate for associated abnormalities.

Specialist centres can provide coordinated care and help prepare for potential neonatal needs if the diagnosis is confirmed. This includes liaising with paediatric specialists, planning delivery location and timing, and providing psychological support throughout the pregnancy. Early planning ensures the best possible outcomes for both mother and baby.

Modern screening tests for DiGeorge syndrome are highly accurate but it’s important to understand the difference between screening and diagnostic testing. NIPT has a high detection rate for 22q11.2 deletions (around 90% in validation studies), but because the condition is rare its positive predictive value is limited — in general-prevalence populations only a minority of high-chance results are confirmed as true positives. NIPT therefore provides risk assessment rather than a definitive diagnosis, and every high-chance result must be confirmed by diagnostic testing.

Diagnostic confirmation requires chromosomal analysis through amniocentesis or CVS, which can detect the deletion with over 99% accuracy. Ultrasound detection depends on the presence of structural abnormalities, which may not be present in all affected pregnancies, so normal scans do not exclude the condition entirely.

Active research continues into DiGeorge syndrome including studies of improved treatments for immune deficiency, better management of learning and behavioural difficulties, and investigation of long-term outcomes. Research into gene therapy and other novel treatments offers hope for future therapeutic advances.

Prenatal research focuses on improving early detection methods, understanding factors that influence symptom severity, and developing better ways to predict outcomes. Participation in research studies and registries helps advance understanding of the condition and may provide access to new treatments and support approaches.