Most of the children with Di George syndrome and 60% of patients with 
velocardiofacial syndrome exhibit a microdeletion within chromosome 22q11. The 
phenotypic expression of this chromosomal abnormality is highly variable.
PATIENTS: Forty-nine children, 0 to 15 years of age, were demonstrated as 
carriers of a 22q11 microdeletion. The main referral diagnoses were: Di George 
syndrome (19 cases), velocardiofacial syndrome (14 cases); congenital heart 
defect with dysmorphism (9 cases); hypoparathyroidism (2 cases). The 
microdeletion was detected by fluorescent in situ hybridization with probes 
specific of the 22q11 region.
RESULTS: Facial dysmorphism was the only constant feature. A congenital heart 
defect was present in 84% of cases. Significant hypocalcemia was documented in 
51% of cases and thymic hypo or agenesis in 83%. Significant immune deficiency 
was documented in nine cases. The most frequent associated defects were urinary 
tract malformations (8 cases). A cleft palate was present in height enfants but 
velopharyngeal insufficiency was almost constant. Two-thirds of children had 
psychomotor delay, and five children exhibited behavioral problems. Of the 35 
couples of parents tested, eight mothers were found to be carriers of the 
deletion.
CONCLUSION: For the pediatrician, it is essential to know the variability of the 
clinical picture. The long-term prognosis is conditioned by the possibility of 
mental retardation and learning disabilities. Parents should be tested for the 
presence of the deletion. The occurrence of the microdeletion in asymptomatic 
relatives raises difficult problems in genetic counselling.