Terminal deletion of the short arm of chromosome 5.

Three cases of deletion of the short arm of chromosome 5 are described: one family cluster, in which the mother and three sons are affected, and two sporadics without the typical "cri du chat" phenotype (the family and Case 2 were previously reported in 1982). Mental retardation varied between affected members of the same family. Band p15.2 appears critical for the development of the complete phenotype. A peculiar deafness observed in the familial and one of the sporadic cases suggests a cochlear malformation.