Williams syndrome: autosomal dominant inheritance.

Williams syndrome (WS) usually occurs sporadically. Few familial cases of Williams syndrome have been described, and those reports have often lacked photographic documentation. We describe 3 families, including a 3-year-old boy and his 34-year-old father, a 2-year-old girl and her 30-year-old mother, and a 3-year-old girl and her 31-year-old mother. None of these patients has supravalvular aortic stenosis or chromosome abnormalities. In all 3 families, the parent with Williams syndrome was diagnosed after the identification of the syndrome in the affected child.