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 individuals with cri-du-chat syndrome. Fluorescent in situ hybridization analysis was used to confirm a terminal deletion karyotype and map more precisely the location of the deletion breakpoint. We identified terminal deletion breakpoints mapping from 5p15.2 to 5p13. Developmental assessment was performed using the Vineland Adaptive Behavior Scales test. Composite Vineland Scores ranged from 20-75. In general, the communication score was higher than the composite score. Comparison of the size of the deletion with the composite Vineland score, as well as the Vineland Communication score, demonstrated 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 achievement.