Cri du Chat-syndrome mit Chromosomenmosaik 46, XY/46, XY, 5p-

Summary The case of a 2;5 year old boy with the typical features of the Cri du Chatsyndrome is described. The cytogenetical examination of lymphocytes and fibroblasts revealed a mosaicism with an approximated 1:1 relation between normal cells and cells with a deletion of the short arm of a B-chromosome. Autoradiography proved the deleted chromosome to be a chromosome No. 5.