Excess of Rare Variants in Non–Genome-Wide Association Study Candidate Genes in Patients With Hypertriglyceridemia

Background— Rare variant accumulation studies can implicate genes in disease susceptibility when a significant burden is observed in patients versus control subjects. Such analyses might be particularly useful for candidate genes that are selected based on experiments other than genome-wide association studies (GWAS). We sought to determine whether rare variants in non-GWAS candidate genes identified from mouse models and human mendelian syndromes of hypertriglyceridemia (HTG) accumulate in patients with polygenic adult-onset HTG. Methods and Results— We resequenced protein coding regions of 3 genes with established roles ( APOC2, GPIHBP1 , LMF1 ) and 2 genes recently implicated ( CREB3L3 and ZHX3 ) in TG metabolism. We identified 41 distinct heterozygous rare variants, including 29 singleton variants, in the combined sample; in total, we observed 47 rare variants in 413 HTG patients versus 16 in 324 control subjects (odds ratio=2.3; P =0.0050). Post hoc assessment of genetic burden in individual genes using 3 different tests suggested that the genetic burden was most prominent in the established genes LMF1 and APOC2 , and also in the recently identified CREB3L3 gene. Conclusions— These extensive resequencing studies show a significant accumulation of rare genetic variants in non-GWAS candidate genes among patients with polygenic HTG, and indicate the importance of testing specific hypotheses in large-scale resequencing studies.