Williams syndrome (WS) is a genetic disorder that affects many parts of the body.[3] Facial features frequently include a broad forehead, short nose and full cheeks, an appearance that has been described as "elfin".[3][5] Mild to moderate intellectual disability with particular problems with visual spatial tasks such as drawing and fewer problems with language are typical.[3] Those affected often have an outgoing personality and interact readily with strangers.[3][5] Problems with teeth, heart problems, especially supravalvular aortic stenosis, and periods of high blood calcium are common.
Williams syndrome is caused by a genetic abnormality, specifically a deletion of about 27 genes from the long arm of one of the two chromosome 7s.[3][5] Typically this occurs as a random event during the formation of the egg or sperm from which a person develops.[3] In a small number of cases, it is inherited from an affected parent in an autosomal dominant manner.[3] The different characteristic features have been linked to the loss of specific genes.