Cri-du-chat syndrome in a child with a 5/15 translocation and interstitial centromeric heterochromatin.

A child is described with most of the typical clinical features of the cri-du-chat syndrome. G- and C-banding studies revealed the karyotype 45,XX, -5, -15, +tdic (5;15) with the loss of short arm material from chromosome 5. Centromeric heterochromatin of the translocated No. 15 is still present in the translocation chromosome. However, no silver precipitation after AgNO3-staining was observed on the translocation chromosome, thus indicating a loss or genetic inactivation of the NOR-region of the translocated No. 15. These cytogenetic results and their possible relationship to the cri-du-chat phenotype are discussed.