Genetic evidence that mutations in the COL1A1, COL1A2, COL3A1, or COL5A2 collagen genes are not responsible for mitral valve prolapse.

DNA markers were used to assess the segregation of genes encoding the collagen types that predominate in the mitral valve (types I, III, and V) in two family pedigrees that are phenotypically different but showed dominantly inherited mitral valve prolapse. The inheritance of these markers was compared with the segregation of the phenotype for mitral valve prolapse in both families. In one family it was shown that the COL1A1, COL1A2, COL3A1, and COL5A2 genes segregated independently of the phenotype; in the other family the results for COL1A1, COL1A2, and COL5A2 were similar but analysis at the COL3A1 locus was not possible. These data indicate that in these families mitral valve prolapse does not arise from a defect in one of these collagen genes.