APOE p.(Leu167del) variant in hypercholesterolemia: Prevalence & phenotypic expression

Abstract

Background: The APOE p.(Leu167del) variant has been identified as a rare cause of autosomal dominant hypercholesterolemia. A comprehensive phenotypic profile of carriers remains undefined, and its frequency has not been systematically studied.

Objective: To characterize the phenotypic differences between p.(Leu167del) carriers among individuals with primary hypercholesterolemia and those with familial hypercholesterolemia (FH), and to estimate the variant's frequency in different populations.

Medthods: Phenotypic differences were assessed from the Lipid Unit cohort of the Hospital Universitario Miguel Servet (HUMS, n = 6489). The allele frequency of the p.(Leu167del) variant was estimated using data from the HUMS and Aragon Workers Health Study (AWHS, n = 5678), a cohort of working adults, and international cohorts: GnomAD (n ≈ 807,162), TOPMed (n ≈ 180,000), 100 K Genomes Project (n ≈ 85,000). To characterize the profile of carriers, data from the HUMS cohort and a systematic review of the published literature were also used.

Results: Carriers showed significantly higher high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, and non-HDL cholesterol and lower lipoprotein(a) [Lp(a)] concentrations compared to noncarriers with primary hypercholesterolemia. In comparison with FH patients carrying LDL receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin/kexin type 9 (PCSK9) variants, carriers displayed higher triglycerides and HDL cholesterol but lower LDL cholesterol and Lp(a). The APOE p.(Leu167del) frequency is approximately 1 in 12,000 individuals in the general population and about 2.5% of FH.

Conclusion: The study confirmed the association of APOE p.(Leu167del) with hypercholesterolemia but with lower LDL cholesterol than subjects with FH. These findings support p.(Leu167del) as a cause of FH and its inclusion in the genetic screening for FH, particularly in Caucasian populations.

Keywords: APOE; Familial hypercholesterolemia; Genetic hypercholesterolemia; Lipid metabolism; p.(Leu167del).