A rare genetic disorder first described by J.C.P. Williams of New Zealand, characterized by an abnormality on chromosome seven.

Williams syndrome (WS) is a genetic disorder first described by J.C.P. Williams of New Zealand. It is estimated to occur in about 1 in 20,000 births. Research has indicated that individuals with Williams syndrome have a chromosomal abnormality. A blood test technique known as the fluorescent in situ hybridization (FISH) may be used to detect the deletion of the elastin gene on chromosome #7 of the individual's DNA. This chromosomal abnormality confirms the diagnosis of Williams syndrome. Williams syndrome is present from birth, although it often remains undiagnosed until a later stage of