22q11.2 Deletion Syndrome (DiGeorge/VCFS)
ABGC-listedListed on the ABGC Self-Study GuideLog in to starLast updated 2mo ago
Log in to add personal notes on this page.
A newborn with Tetralogy of Fallot is noted to have hypocalcemia and absent thymic shadow on chest X-ray. He has subtle facial features including hooded eyelids and a bulbous nasal tip. FISH confirms a 22q11.2 deletion.
- Most common microdeletion syndrome (~1/4,000 live births)
- Deletion: 22q11.2 (~3 Mb in 90%, ~1.5 Mb in 10%)
- Includes TBX1 gene (cardiac/thymic/parathyroid development)
- ~90% de novo; 10% inherited (AD with variable expression)
- Cardiac: conotruncal defects (TOF, interrupted aortic arch, truncus arteriosus, VSD)
- Hypocalcemia (hypoparathyroidism)
- Immune deficiency (thymic hypoplasia)
- Palatal abnormalities: VPI, cleft palate, hypernasal speech
- Characteristic facies: hooded eyelids, bulbous nose, small ears
- Learning disabilities, psychiatric illness (schizophrenia risk ~25%)
- CMA or FISH for 22q11.2
- Always test newborns with conotruncal heart defects (TOF, interrupted aortic arch, truncus arteriosus)
- Parental testing indicated once a proband is identified (autosomal dominant; ~10% inherited from a mildly affected parent)
- Multidisciplinary care: cardiology, immunology, endocrinology, ENT/speech, developmental support
- Cardiac surgical repair of conotruncal defects; monitor calcium perioperatively
- Monitor and treat hypocalcemia (calcium, vitamin D); endocrine follow-up
- Immune evaluation before live vaccines; avoid in significant T-cell deficiency
- Speech therapy and palate/VPI surgical evaluation; developmental and educational services
- Psychiatric surveillance through adolescence and adulthood (anxiety, ADHD, psychosis risk)
CATCH 22: Cardiac defects, Abnormal facial features, Thymic hypoplasia, Cleft palate, Hypocalcemia, chromosome 22.