Williams syndrome and behavioral phenotypes in human microdeletion syndromes

A specific behavioral phenotype is recognized in some genetic entities, par ticularly in microdeletion syndromes secondary to cytogenetically undetecta ble chromosomal deletions. Williams syndrome (WS) is a development disorder displaying dysmorphic signs, heart malformations and behavioral phenotype associated, in most cases, with a deletion of chromosome 7q11.23. We descri bed physical and neuro-psychological assessment of nine cases of SW. Molecu lar studies were performed using Southern blot analyses of FISH, and identi fied a 7q11.23 deletion in all cases. Behavioral phenotype of WS is charact erized by hyperactivity, engaging and jovial personality, hypersensitivity in hearing and some elements of speech may be enhanced. Moderate mental ret ardation is frequently present. Previously reported studies have revealed s pecific cognitive deficits including deficits in language development and i n long term memory and poor visual-motor integration. Two genes LIMK1 and S TX1A have been supposed to be implicated in determinated of WS microdeletio n syndromes focusing attention on some chromosomal regions supposed to cont ain candidate genes involved in cognitive and behavioral traits.