Floppy mitral valve/mitral valve prolapse: A complex entity with multiple genotypes and phenotypes.

Floppy mitral valve/mitral valve prolapse (FMV/MVP) is a common valvular abnormality affecting 2% to 3% of the general population. It occurs in a heterogeneous group of patients with varying and age dependent expressions. FMV/MVP can be familial or sporadic, isolated (called non-syndromic) or as a part of a well-defined syndrome of heritable connective tissue disorders or other diseases. A wide range of phenotypic expression exists ranging from asymptomatic to non-specific symptoms related to neuroendocrine or autonomic nervous system functional abnormalities, varying degrees of mitral regurgitation that may require interventional therapy, heart failure, infective endocarditis, cardiac arrhythmias and/or sudden cardiac death. FMV/MVP is predominantly considered a heritable disorder with clinical manifestations not present at birth, but appearing later in life. Though a variant gene may initiate the development of FMV/MVP, precise phenotypic expression may be related to multiple other molecular, genetic and epigenetic factors that modify the final expression of the disease. A better understanding of these mechanisms will help to better define the natural history of the disease, inhibit disease progression and even prevent the phenotypic expression of FMV/MVP.