Background: Mitral valve prolapse (MVP) is one of the most common valvular heart disorders. Twenty percent of MVP patients will develop severe complications, including congestive heart failure, endocarditis, atrial arrhythmias, embolic events and even sudden death. MVP is the most common cause of mitral regurgitation requiring surgical repair, however, very little is known about its etiology. MVP has a strong genetic background with significant heterogeneity. Previous genetic studies have shown that non-syndromic MVP can be caused by mutations in filamin A, and the applicant’s group has identified two additional genetic loci, MMVP2 and MMVP3, on chromosomes 11 and 13. In this study we propose to identify the gene for MMVP2 using next-generation sequencing analysis, and to analyze additional families to further define the molecular pathways that lead to the development of MVP.Aims: The aims of this proposal are to 1) identify the gene for MMVP2 using next-generation sequencing and 2) identify MVP-causing mutations in families segregating the disease by whole-genome family-based linkage analysis, positional cloning and parallel sequencing.Methods: A DNA library representing MMVP2 locus of 4 affected individuals was already prepared and will be sequenced. After sequencing we will validate potential mutation by replicating in nearly 200 familial and sporadic MVP cases. Newly recruited families segregating MVP will be queued for a whole-genome linkage analysis to identify MVP susceptibility loci. DNA of the targeted regions in affected individuals will be pooled and sequenced using next-generation parallel sequencing in search for sequence variation. The pathogenicity of sequence variations will be determined by verifying their segregation with disease in the pedigree, by assessing their effect on protein structure and expression using bioinformatic tools, and by comparing their frequency in cohorts of patients and controls.Expected results and probable impl