Duplication of distal 11q and 22p occurrence in two unrelated families.

We report chromosome rearrangements and/or duplication of chromosomes 11 and/or 22. This investigation was prompted by propositi with multiple congenital anomalies and an apparently identical chromosome abnormality - ie, 47, +der(22)t(11;22)(q23;q11.2)mat in two unrelated families. The propositi had failure to thrive, development delay, cleft palate, congenital heart disease, meningomyelocele, and hydrocephaly. The breakage points identified on chromosomes 11 and 22 are site-specific and occur in a nonrandom fashion. Band 11q23 corresponds to the gap produced in some individuals by special treatment of the chromosome preparation with mercaptoethanol and may provide a method to identify individuals at risk for chromosome breakage and rearrangements during gametogenesis.