GCKR and hypertriglyceridemia: We therefore aimed to characterize extensively all rare, non-synonymous GCKR variants identified through sequencing of individuals with hypertriglyceridemia and controls with normal plasma triglyceride levels in a range of functional assays, to evaluate the performance of in silico tools for assigning pathogenicity, and to investigate the penetrance and heritability of rare GCKR variants by exploring co-segregation between heterozygous carriers of functional variants and metabolic phenotypes in families.