Karyotype instability with multiple 7/14 and 7/7 rearrangements.

Chromosomes were studied in a mentally retarded boy with microcephaly, growth retardation, facial erythema, café-au-lait spots, and IgA deficiency. In the lymphocytes there was a remarkable tendency to exchange parts of the chromosomes Nos. 7 and 14, the translocations almost exclusively taking place in bands 7p13, 7q32 and 14q11. Seven different types of rearrangements between Nos. 7 and 14, and some other chromosomal aberrations were found. No abnormalities could be detected in the bone marrow. The patient somewhat resembles those affected with ataxia-telangiectasia or with Bloom's syndrome, but on clinical and cytogenetic grounds these disorders could be excluded. 7/14 Translocations similar to those found in our patient's lymphocytes have been reported to occur very rarely in the lymphocyte cultures of individuals with apparently normal chromosome constitution. A relationship between these phenomena may exist.