A family study of anterior mitral leaflet thickness and mitral valve prolapse.

To determine whether mitral valve prolapse (MVP) with or without mitral leaflet thickening (> or =5 mm) represents distinct heritable conditions, 13 patients with MVP with leaflet thickening and their relatives were compared with 67 patients with MVP with normal leaflets and their relatives. The 2 groups of relatives had similar mitral leaflet thicknesses and similar long-term outcome, arguing against the existence of a distinctive subtype of MVP characterized by increased mitral leaflet thickness.