another chromosomal locus for mitral valve prolapse. Close, but no cigar. Circulation 2005

The mitral valve forms a complex apparatus whoseclosing and opening with the heartbeat coordinates theflow of blood from the left atrium to the left ventricle. In an average human life span, it does a command perfor-mance to the tune of 3 billion heartbeats. During the life span, the leaflets experience significant wear and tear exhib-ited by a thickening of the outer silk lining, but performance in most individuals remains graceful and relatively unde-terred. This synchronized dance to the rhythm of the heart-beat, a rhythm which changes in response to emotional, mental, and physical demands, appears effortless and relent-less. 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 physica