Developmental and cognitive troubles in Williams syndrome.

Williams syndrome (WS) is a neurodevelopmental genetic disorder with a prevalence of approximately 1 in 7500. It is caused by a hemizygous deletion of approximately 28 genes on the 7th chromosome (7q11.23), including the elastin allele. Individuals with WS have atypical facial characteristics, including medial eyebrow flair, epicanthal folds, upturned nose, elongated philtrum, and full lips. Infants typically experience constipation and colic. Cardiac and renal abnormalities, as well as hypertension, are common. Individuals with WS are at increased risk for hearing and vision difficulties. Gastrointestinal difficulties are common and include constipation and diverticulitis. Joint abnormalities are observed in both children and adults with WS. Individuals with WS are overly friendly yet can experience nonsocial anxieties. Cognitive skills are typically in the mild to moderately delayed range. Relative strengths have been demonstrated in some aspects of language and face processing, while visuospatial skills are significantly delayed.