The K23 Award will support rigorous training for the development of a career as an independent translational investigator with a focus on the genetics of mitral valve prolapse (MVP) and its progression. The principle investigator has completed a fellowship in cardiology and advanced imaging at Beth Israel Deaconess Medical Center (BIMDC) and a fellowship in echocardiography at Massachusetts General Hospital (MGH). The candidate has gained expertise in linkage analysis studies and phenotypic-genotypic correlations. As a staff cardiologist at BIDMC, she is now seeking new skills in genetic epidemiology and genome-wide association studies (GWAS). She will have access to a state-of-the-art genotyping facility (FHS), and echocardiography laboratories (BIDMC and FHS). Her multidisciplinary mentoring team includes experts in GWAS (Dr Ramachandran), and valvular disease/echocardiography (Drs Manning and Levine). A Master of Public Health in Clinical Effectiveness (Harvard School of Public Health) will provide the coursework necessary for her academic success. Although MVP is the most common cause of isolated mitral regurgitation (MR) requiring surgical repair, little is known about the genetic determinants of MVP and its progression. To date, 3 loci for autosomal dominant MVP have been described on chromosomes 11, 16 and 13, but gene finding has proved elusive. In addition, while the prevalence of MVP in the community is 2-5%, the prevalence of familial MVP is unknown. In the chromosome 13 family, previously non-diagnostic morphologies often represent early stages of expression in gene carriers and share two salient features with fully diagnostic MVP: an anteriorly displaced coaptation point and posterior leaflet asymmetry. This proposal tests the hypotheses that early stages of MVP exist and can progress in the FHS community, and that MVP heritability is high. In addition, several MVP loci can be identified through a multicenter GWAS. To test these hypotheses, the candidate will: 1) Measure mitral leaflet coaptation height, displacement, thickness, and degree of MR by echocardiography in the FHS Offspring Cohort and in a hospital-based sample (BIDMC) at baseline and at available follow-up of 11-17 (FHS) and 5 years (BIDMC). 2) Evaluate the presence of MVP in Gen 3 individuals whose parents in the Offspring Cohort have MVP. High MVP heritability would lead to specific gene-finding strategies such as whole-exome analysis and clarify if routine screening of family members in the community is warranted. 3) Search for MVP loci using GWAS both in FHS and in other US and European cohorts (>2500 MVP subjects) (Leducq MITRAL Network).
These aims represent crucial steps towards future gene-finding strategies and understanding of the variability of progression and clinical outcomes among MVP patients in the community, with the potential of developing therapeutic targets to prevent progression at an early stage.
Mitral valve prolapse (MVP) is a common disorder occurring in 2-5% of the population, and characterized by displacement of one or both leaflets into the left atrium. Although MVP is the most common cause of isolated mitral regurgitation requiring surgical repair, little is known about the genetic mechanisms underlying its genesis and progression. Previous studies in families with MVP have shown that early, non-diagnostic forms of MVP often represent early stages of expression in gene carriers. This proposal aims at identifying these prodromal morphologies in the community, assessing their progression, and revealing the genetic determinants involved in the genesis of MVP. These represent crucial steps towards understanding of variability of progression and outcomes among MVP individuals, with the potential of developing therapeutic targets at an early stage.
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