0131: A phenotypic study of ARHGAP24 mitral valve prolapse suggests a genetic origin for fibro elastic deficiency

Mitral valve prolapse (MVP) by Barlow disease is recognized a genetic disease. Fibro-elastic deficiency (FED)-MVP is considered a pure degenerative condition. FLNA, the first gene involved in MVP, encodes for Filamin-A, a cytoskeleton associated protein. It interacts with a protein named Filgap, encoded by ARHGAP24 (Chr. 4), in the mechanical transduction. We hypothesized that ARHGAP24 mutations could elicit MVP with same pathway.Four probands with ARHGAP24 mutations were identified among 96 MVP. By a familial echocardiographic screening we enrolled 19 adults of whom 13 had an ARHGAP24 mutation. The mutated group was matched with a control group of 39 healthy adults. Anterior (AML) and posterior (PML) mitral leaflets length and thickness were measured. The coaptation point position was the ratio of coaptation height on the systolic annulus diameter. MVP (displacement>2mm above the annulus line), minimal systolic displacement (MSD, displacement<2mm) and abnormal antero-posterior coaptation position (AAC, ratio