Report of a rare case of congenital mitral valve prolapse with chronic kidney disease--reconsidered genotype-phenotypic correlations.

BACKGROUND: Mitral valve prolapse (MVP) is a common cardiovascular disease defined as a late systolic click or mitral valve lobes that move up into the left atrium during ventricular systole, with or without mitral insufficiency. Dachsous catherin-related 1 (DCHS1) is one of the two known pathogenic genes associated with MVP. However, there is little information about the renal dysfunction caused by MVP and DCHS1 mutations.
METHODS: We analyzed the genetic etiology in a rare case of 9-year-old boy affected by chronic renal failure with MVP. Subsequently, we constructed stable cell lines overexpressing wild-type DCHS1 or mutant DCHS1 (c.8309G>A, p.R2770Q) to evaluate the influence of the DCHS1 mutation on the proliferation, apoptosis, and autophagy.
RESULTS: Complete exome sequencing and pedigree verification revealed a mutation p.R2770Q (c.8309G>A) in exon 21 of the DCHS1 gene carried by the patient, which may affect the DNA binding. No such mutation was detected in his parents, indicating that this was a new mutation. Potential functional impact of sequence variants was predicted using in silico prediction programs including SIFT, Polyphen2, and Condel. This variant was determined to be a pathogenic mutation that has not been reported elsewhere. Subsequently, we used a stable DCHS1 gene-mutated HK-2 cell line to analyse proliferation, apoptosis, and autophagy, showed that kidney volume decreased with increasing cell death associated with a reduced proliferation.
CONCLUSIONS: Our analysis revealed a heterozygous variation of DCHS1 in a child with MVP. Our observations highlight previously unrecognized phenotypes of the currently recognized MVP genotype, including distinct chronic renal failure.