Mitral valve prolapse syndrome and MASS phenotype: Stability of aortic dilatation but progression of mitral valve prolapse.

Background: Mitral valve prolapse syndrome (MVPS) and MASS phenotype (MASS) are Marfan-like syndromes that exhibit aortic dilatation and mitral valve prolapse. Unlike in Marfan syndrome (MFS), the presence of ectopia lentis and aortic aneurysm preclude diagnosis of MVPS and MASS. However, it is unclear whether aortic dilatation and mitral valve prolapse remain stable in MVPS or MASS or whether they progress like in MFS.