Biological determinants of the origin and development of the opposite psychological and behavioral traits associated with autism spectrum disorders and Williams syndrome

Williams syndrome is a genetical disorder caused by microdeletion on chromosome 7, specifically of 7q11.23 region. Its phenotype is characterized by typical facial features, mild mental retardation, cardiovascular problems (patients often suffer from supravalvular aortic stenosis), gastrointestinal problems and endocrine abnormalities. However, Williams syndrome is best known for its unique behavioural-cognitive profile which leads to friendly, hypersocial and talkative personality. This specific neuropsychological profile is repeatedly considered to be the right opposite of the psychological profile, which is characteristic for people with autism spectrum disorder. Individuals with autism spectrum disorder often have severe impairments in social interaction, communication and they suffer from social anxieties. This contrasting cognitive-behavioural phenotype inspired many studies to examine possible biological causes, which might determine given personality features. Several results from these studies suggest that small genetical TFII-I family, which lies in the critical Williams syndrome region, could have a significant impact on the extent of personality qualities such as sociality and communication.