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1. Introduction: What is 22q11.2 Deletion Syndrome?
22q11.2 deletion syndrome occurs when a small section of the long arm (q) of chromosome 22, at position 11.2, is missing.
It was formerly referred to as DiGeorge syndrome or Velocardiofacial Syndrome (VCFS), but today the umbrella term “22q11.2 deletion syndrome” is used.
This syndrome is characterized by diverse clinical features, including developmental delay, intellectual disability, congenital heart defects, immune deficiency, and psychiatric disorders.
It occurs in about 1 in 4,000 live births, less common than the three major trisomies (e.g., Down syndrome), but relatively frequent among microdeletion syndromes.
2. Key Symptoms and Clinical Features
22q11.2 deletion syndrome presents with a wide range of symptoms:
- Intellectual and learning disabilities
Most individuals have mild to moderate intellectual disability (IQ 50–70)
ADHD or learning disabilities may also occur - Neurodevelopmental and psychiatric risks
Autism spectrum disorder (ASD)-like social and communication difficulties
Increased risk of schizophrenia in adolescence or adulthood - Congenital heart defects
Examples include tetralogy of Fallot and aortic arch anomalies - Immune and endocrine abnormalities
Cellular immune deficiency due to thymic hypoplasia
Seizures caused by hypocalcemia
3. Relationship with Intellectual Disability
Around 70% of patients show mild to moderate intellectual disability or developmental delay.
- Mild (IQ 50–69): may achieve partial independence with educational support
- Moderate (IQ 35–49): usually requires continuous daily life support
Language delay is common, and speech may be unclear due to articulation difficulties or velopharyngeal insufficiency.
Early developmental interventions and special education significantly improve learning and social outcomes.
4. What NIPT Can and Cannot Detect
NIPT (Non-Invasive Prenatal Testing) analyzes cell-free fetal DNA in maternal blood to screen for chromosomal abnormalities.
- Traditionally detected by NIPT:
Trisomy 21 (Down syndrome)
Trisomy 18 (Edwards syndrome)
Trisomy 13 (Patau syndrome) - Recent advances:
Some NIPT panels now screen for microdeletion syndromes, including 22q11.2 deletion syndrome
NIPT can detect:
- Risk of 22q11.2 deletion and certain other microdeletion syndromes
- The three major trisomies
NIPT cannot detect:
- Autism, ADHD, or other neurodevelopmental disorders not caused by deletions
- Definitive diagnosis (positive results require amniocentesis or genetic testing)
5. Confirmatory Diagnosis and Genetic Counseling
If NIPT suggests a high risk, confirmatory tests are required, such as:
- Amniocentesis
- Genetic testing (e.g., FISH, CGH array)
Why genetic counseling is essential:
- Symptom severity and prognosis vary widely
- Allows families to plan early medical and educational support
- Provides guidance for family planning and psychological support
6. Impact on Families and Society, and Available Support
Many affected infants need medical care immediately after birth, requiring long-term family support.
- Medical support: pediatric cardiology, immunology, endocrinology, and multidisciplinary care
- Educational support: early intervention, special education services
- Psychosocial support: family and patient organizations, social security (disability handbooks, allowances)
These supports help improve quality of life (QOL).
7. Key Takeaways
- 22q11.2 deletion syndrome often involves intellectual disability, developmental disorders, and heart defects
- NIPT can detect risk prenatally, but confirmation requires invasive testing
- Early establishment of medical, psychological, and social support systems is critical
8. Importance of Prenatal Diagnosis
Traditionally diagnosed after birth, this condition can now be identified prenatally with NIPT.
Advantages of prenatal detection:
- Immediate postnatal medical intervention (e.g., cardiac surgery, immune treatment)
- Advance planning for NICU admission and surgery
- Time for families to prepare emotionally and practically
- Early initiation of multidisciplinary care
Limitation: severity cannot be predicted precisely before birth.
9. Psychological Impact and Family Decisions
- Anxiety and dilemmas
“Can we raise a child with special needs?”
Difficult decisions about pregnancy continuation - Family disagreements
Different values between partners or extended family members - Need for psychological support
Counseling from psychologists and genetic counselors is vital
Parent networks and support groups provide additional reassurance
10. Social and Ethical Considerations
Social perceptions of disability
Wider acceptance and support for families with disabled children are essential as prenatal testing becomes more common
Selective termination debates
Decisions about continuing or terminating a pregnancy carry ethical challenges
Genetic counseling is required by medical guidelines
Information asymmetry
Knowledge gaps between healthcare providers and families can cause misunderstandings
11. Future Research and Medical Outlook
- Genomic advances:
More accurate screening for microdeletions and duplications
Improved prediction of psychiatric risks at the gene level - Early intervention and personalized care:
Infant developmental programs to improve language and social skills
Lifelong individualized medical-educational care models - Social and legal progress:
Stronger ethical frameworks and counseling systems
Better societal support for families raising children with disabilities
12. Conclusion
- 22q11.2 deletion syndrome is a chromosomal microdeletion disorder with diverse symptoms, including intellectual and developmental disabilities
- NIPT can identify risks prenatally, but definitive diagnosis requires invasive testing
- Due to wide variation in severity, genetic counseling, psychological support, and social preparation are essential
- Future priorities include early diagnosis, personalized support, and expanded social understanding
