Abstract 15418: Mir590 Variant rs6971711 Identified in African-American HCM Patients Reduces Mature MiR590 Biogenesis and Target Gene Expression

Hypertrophic cardiomyopathy (HCM), the most common inherited cardiovascular disorders characterized by myocyte hypertrophy/disarray and fibrosis. Genotype-phenotype correlations indicate phenotypic heterogeneity and variable penetrance, indicating influence of modifier genes. Recent studies reveal that variants in microRNAs (miRs) can lead to disease. Aim: The goal was to identify genetic variations in miRs that could have functional effects, in HCM patients. Methods: Direct sequencing of 18 miRs (selected by literature mining) was performed in 199 HCM patients. The 1000 Genomes Project database was used to obtain matched population allele and genotype frequency. Real-time qPCR and luciferase assay were performed in HEK293T cells to assess functional effects of the miR variant. Results: Eleven variants in 9/18 miRs were identified in 89 HCM patients. Our novel result is a SNP rs6971711 (72C>T) , located in mature miR-590-3 p , a regulator of post-natal cardiac myocyte proliferation. This SNP was present in 5 patients, all African-Americans. SNP frequency in HCM patients (0.227) was markedly higher than its frequency in the 1000 Genomes Project database. Alignment of pre-miR sequences revealed that rs6971711 is located in a highly conserved region in mammals. Mutant miR-590 (hsa-pri-miR-590; 72T) transfection in HEK293T cells resulted in 9 fold reduction of mature miR-590-5 p levels and 49 fold decrease of miR-590-3 p levels when compared to wild type (hsa-pri-miR-590; 72C), indicating reduced miR-590 biogenesis . The 3’ UTR of TGF-β receptor type II (TGFBR2) was chosen to examine the functional change caused by 72C>T in miR-590 because it is an experimentally-validated miR-590-5 p target and important in TGF-β signaling/fibrosis. Over-expression of wild type miR-590 suppressed luciferase activity ~5fold, while the mutant significantly reduced (p p [[Unable to Display Character: –]] hence the SNP could predispose to cardiac fibrosis. Conclusion: This is the first report of a miR SNP ( rs6971711) with high frequency in African-American HCM patients and loss of function effect on miR-590-3 p /5 p biogenesis and target gene (TGFBR2) suppression, which could influence left ventricular mass and fibrosis.