Fine-mapping of QT regions in global populations refines previously identified QT loci and identifies signals unique to african and hispanic descent populations.

Publication Type:

Journal Article

Source:

Heart rhythm (2016)

Abstract:

BACKGROUND: The electrocardiographically measured QT interval (QT) is heritable and its prolongation is an established risk factor for several cardiovascular DISEASES: Yet, most QT genetic studies have been performed in European ancestral populations, possibly reducing their global relevance.

OBJECTIVE: To leverage diversity and improve biologic insight, we fine-mapped 16 of the 35 previously identified QT loci (46%) in populations of African American (n=12,410) and Hispanic/Latino (n=14,837) ancestry.

METHODS AND RESULTS: The 16 fine-mapped QT loci included on the Illumina Metabochip represented 21 independent signals, of which 16 (76%) were significantly (P-value‚ȧ9.1x10(-5)) associated with QT after inverse-variance weighted trans-ethnic meta-analysis of racial/ethnic-specific multiple linear regression analyses adjusted for heart rate and clinical covariates. Through sequential conditional analysis we also identified three trans-ethnic novel SNPs at ATP1B1, SCN5A-SCN10A, and KCNQ1 and three Hispanic/Latino-specific novel SNPs at NOS1AP and SCN5A-SCN10A (two novel SNPs) with evidence of associations with QT independent of previous identified GWAS lead SNPs. Linkage disequilibrium patterns helped to narrow the region likely to contain the functional variants at several loci, including NOS1AP, USP50-TRPM7, and PRKCA, although intervals surrounding SLC35F1-PLN and CNOT1 remained broad in size (>100 kb). Finally, bioinformatics-based functional characterization suggested a regulatory function in cardiac tissues for the majority of independent signals that generalized and the novel SNPs.

CONCLUSION: Our findings suggest that a majority of identified SNPs implicate gene regulatory dysfunction in QT prolongation, that the same loci influence variation in QT across global populations, and that additional, novel, population-specific QT signals exist.