Incomplete trisomy 22. I. Familial 11/22 translocation with 3:1 meiotic disjunction. Delineation of a common clinical picture and report of nine new cases from six families.

A syndrome due to 3:1 meiotic segregation of balanced 11/22 translocation is defined from nine personally observed patients and 22 cases from the literature with apparently the same aberration. Frequent findings include a characteristic face with deep-set eyes, flat nose, prominent upper lip, receding mandible and preauricular pits or tags, male genital hypoplasia, anal atresia or other anomalies of the anus, cleft palate, and congenital heart defect. Less frequent are severe reduction of the auricles, an additional pair of ribs, and hypoplasia of the diaphragm. Perinatal mortality is high. Growth is usually and psychomotor development is invariably and severely delayed. Balanced 11/22 translocations are apparently disproportionally frequent; as the balanced rearrangement is not easy to detect, it is important to be aware of it at the family investigation of cases with extra chromosomes similar to a No. 22 or 22q-. The unbalanced products are most probably trisomic for both a segment of 22 (22q-) and a distal segment of 11q; the exact determination of the breakpoints is not possible at present due to the similar banding characteristics of the two segments involved in the translocation.