Ancestry-specific profiles of genetic determinants of severe hypertriglyceridemia

Abstract

Susceptibility to severe hypertriglyceridemia (HTG), defined as plasma triglyceride (TG) levels ≥10mmol/L (880mg/dL), is conferred by both heterozygous rare variants in five genes involved in TG metabolism and numerous common single-nucleotide polymorphisms (SNPs) associated with TG levels. To date, these genetic susceptibility factors have been comprehensively assessed primarily in severe HTG patients of European ancestry. Here, we expand our analysis to HTG patients of East Asian and Hispanic ancestry. The genomic DNA of 336, 63 and 199 severe HTG patients of European, East Asian and Hispanic ancestry, respectively, was evaluated using a targeted next-generation sequencing panel to screen for: 1) rare variants in LPL, APOA5, APOC2, GPIHBP1 and LMF1; 2) common, small-to-moderate effect SNPs, quantified using a polygenic score; and 3) common, large-effect polymorphisms, APOA5 p.G185C and p.S19W. While the proportion of individuals with high polygenic scores was similar, frequency of rare variant carriers varied across ancestries. Compared with ancestry-matched controls, Hispanic patients were the most likely to have a rare variant (OR=5.02; 95% CI 3.07-8.21; p<0.001), while European patients were the least likely (OR=2.56; 95% CI 1.58-4.13; p<0.001). The APOA5 p.G185C polymorphism, exclusive to East Asians, was significantly enriched in patients compared with controls (OR=10.1; 95% CI 5.6-18.3; p<0.001), showing the highest enrichment among the measured genetic factors. While TG-associated rare variants and common SNPs are both found in statistical excess in severe HTG patients of different ancestral backgrounds, the overall genetic profiles of each ancestry group were distinct.