It Helps to Know Genetic Basis: Williams Syndrome as an Example of Cognitive Disability

Abstract

When an adequate knowledge base is present, an assessment and intervention approach that takes into account genetic disorder etiology can be particularly powerful for children with genetically based neurodevelopmental disorders (Dykens & Hodapp, 2001). To illustrate the importance of this etiological approach, this case depicts the tailoring of assessment and intervention suggestions to a particular intellectual disability syndrome, Williams syndrome.

Williams syndrome is a genetic disorder resulting from a hemizygous micro-deletion on the long arm of chromosome 7. Genetic testing became available commercially in the early 1990s, consisting of a FISH test (fluorescence in situ hybridization) for the deletion of elastin, one of the genes in the Williams syndrome region. Although the level of intellectual functioning in individuals with Williams syndrome can vary greatly (from moderate intellectual disability to average range intellectual functioning in some), characteristic cognitive and behavioral pheno-types have been identified (Klein-Tasman & Mervis, 2003; Mervis et al., 2000).