Genetic association analyses highlight biological pathways underlying mitral valve prolapse

Non-syndromic mitral valve prolapse (MVP) is a common degenerative cardiac valvulopathy of unknown aetiology that predisposes to mitral regurgitation, heart failure and sudden death(1). Previous family and pathophysiological studies suggest a complex pattern of inheritance(2–5). We performed a meta-analysis of two genome-wide association studies in 1,442 cases and 2,439 controls. We identified and replicated in 1,422 cases and 6,779 controls six loci and provide functional evidence for candidate genes. We highlight LMCD1 encoding a transcription factor(6), for which morpholino knockdown in zebrafish results in atrioventricular (AV) valve regurgitation. A similar zebrafish phenotype was obtained for tensin1 (TNS1), a focal adhesion protein involved in cytoskeleton organization. We also show the expression of tensin1 during valve morphogenesis and describe enlarged posterior mitral leaflets in Tns1(−/−) mice. This study identifies the first risk loci for MVP and suggests new mechanisms involved in mitral valve regurgitation, the most common indication for mitral valve repair(7).