No relationship between the size of the deletion and the level of developmental delay in cri-du-chat syndrome

Molecular cytogenetic and developmental assessment was performed on 50 indi viduals with cri-du-chat syndrome. Fluorescent in situ hybridization analys is was used to confirm a terminal deletion karyotype and map more precisely the location of the deletion breakpoint. We identified terminal deletion b reakpoints mapping from 5p15.2 to 5p13. Developmental assessment was perfor med using the Vineland Adaptive Behavior Scales test. Composite Vineland Sc ores ranged from 20-75. In general, the communication score was higher than the composite score. Comparison of the size of the deletion with the compo site Vineland score, as well as the Vineland Communication score, demonstra ted that there was no correlation between the size of the deletion and the level of developmental delay. These results demonstrate that patients with cri-du-chat syndrome show high variability in the level of developmental ac hievement. Am. J. Med. Genet. 86:66-70, 1999. (C) 1999 Wiley-Liss, Inc.