Association of mitral-valve prolapse with low body-weight and low blood pressure.

Subjects with mitral-valve prolapse (MVP) have been observed to have an asthenic body build. To determine whether body-weight differed between individuals with inherited MVP and normal subjects, 177 relatives of 45 patients with MVP were studied, 35 female and 19 male relatives had MVP, and 51 female and 72 male relatives did not. There was no difference in mean height between relatives with and without MVP, but those with MVP weighed significantly less. Blood pressure was also significantly lower in relatives with MVP than in normal relatives. It is suggested that the lower blood pressure and the possible beneficial effects of lower weight on other cardiovascular risk factors may provide a selective advantage to carriers of the MVP gene, explaining its high prevalence in the general population. These findings may provide the first example of a common inherited condition which is systematically associated with changes in body-weight and blood pressure.