ELN and familial mitral valve prolapse: The changes observed in mitral valves, such as leaflet lengthening, tip thickening, marked accumulation of GAGs, and overall increase in collagen and elastin, are similar to those described in human MFS subjects, of which 25% had clinical evidence of myxomatous mitral valve phenotype (20), as well as in primary MVP, where the majority of patients have no identifiable genetic mutation or syndrome (21).