Another Chromosomal Locus for Mitral Valve Prolapse

Abstract

The mitral valve forms a complex apparatus whose closing and opening with the heartbeat coordinates the flow of blood from the left atrium to the left ventricle. In an average human life span, it does a command performance to the tune of ≈3 billion heartbeats. During the life span, the leaflets experience significant wear and tear exhibited by a thickening of the outer silk lining, but performance in most individuals remains graceful and relatively undeterred. This synchronized dance to the rhythm of the heartbeat, a rhythm which changes in response to emotional, mental, and physical demands, appears effortless and relentless. Beneath this superficial and necessary display, however, lurks many opportunities for a misstep. There have been decades of statistics suggesting that abnormalities in the mitral valve are common—2% to 16%.1–5 The symptoms, when present, are vague and include dizziness, palpitations, syncope, atypical chest pain, and dyspnea. On physical examination, the presence of a click or murmur often positions the patient for multiple tests, which can be a source of great emotional concern. Once the observation came that diet pills were associated with valvular dysfunction, echocardiographic analysis demanded by lawyers from urban billboards uncovered many patients with mitral valve prolapse and lifted the diagnosis to a new level of notoriety.6 See p 2022 In the past 10 years, improved technology and community studies rather than hospital-based studies have ascertained a prevalence of ≈2.4%.7,8 This reduced prevalence is in part the result of better understanding of the 3-dimensional architecture of the mitral valve annulus provided by 3-dimensional echocardiography. This led to standardized echocardiographic criteria for the diagnosis of mitral valve prolapse.9,10 Classic mitral valve prolapse is diagnosed if upward displacement of the leaflet exceeds 2 mm and maximal thickness is ≥5 mm; nonclassic mitral valve prolapse refers to …