A new and rare form of Williams' syndrome.

A 7 year old girl and her mother have typical phenotypic features of the Williams' (elfin facies) syndrome, and both have only mild mitral regurgitation with mitral valve prolapse (MVP). Mitral valve prolapse has been reported in only three cases but pure mitral insufficiency has not been reported alone. In this paper two cases of a new rare form of Williams' syndrome with MVP are presented and this rare disorder is discussed.