Repeated unbalanced offspring due to a familial translocation involving chromosomes 5 and 6

We identified 10 members of a single family with mental retardation and mic rocephaly, one member having macrocephaly instead. The pedigree was best co mpatible with the segregation of a small translocation, despite results of previous cytogenetic studies in several relatives being apparently normal. Eventually high resolution and fluorescence in situ hybridization studies i n the parents allowed the detection of a balanced translocation between 5qt er and 6qter, and of its unbalanced products in the offspring, The pertinen t findings from the family are briefly compared with the clinical findings in patients from the literature with either a duplication or deletion of 5q 35-ter, or a duplication or deletion of 6q27-ter. Am. J, Med, Genet, 80:448 -453, 1998, (C) 1998 Wiley-Liss, Inc.