Williams syndrome: From genotype through to the cognitive phenotype

Williams syndrome, due to a contiguous gene deletion at 7q11.23, is associa ted with a distinctive facial appearance, cardiac abnormalities, infantile hypercalcemia, and growth and developmental retardation. The deletion is ap proximately 1.5Mb and includes similar to 17 genes. Large repeats containin g genes and pseudogenes flank the deletion breakpoints, and the mutation me chanism commonly appears to be unequal meiotic recombination. Elastin hemiz ygosity is associated with supravalvular aortic stenosis and other vascular stenoses. LIM Kinase 1 hemizygosity may contribute to the characteristic c ognitive profile. The relationship of the other deleted genes to phenotypic features is not known. People with Williams syndrome tend to be over friendly-though anxious-and l ack social judgement skills. They exhibit an uneven cognitive-linguistic pr ofile together with mild to severe mental retardation. Analysis of the cogn itive phenotype based on analyses of the mental processes underlying overt behavior demonstrates major differences between normal and WS subjects alth ough for some areas, such as face processing, WS subjects can achieve near normal scores. Cognitive analysis of patients with small deletions in 7q11. 23 which include elastin and LIM Kinase 1 have revealed varying results and it is premature to draw genotype-phenotype correlations. (C) 2000 Wiley-Li ss, Inc.