Impact of variants of uncertain significance of LDL receptor on phenotypes of familial hypercholesterolemia

Data on the effect of variants of uncertain significance (VUS) of LDL receptor (LDLR) on familial hypercholesterolemia (FH) phenotype is limited.To investigate the associations between genotypes and phenotypes, including low-density lipoprotein (LDL) cholesterol level and occurrence of major adverse cardiac events (MACEs), in FH patients (N = 1050, male/female = 490/560).We retrospectively assessed the data of patients with FH admitted at Kanazawa University Hospital between 1990 and 2020. Based on genotype, the patients were divided into patients without variants, with VUS of LDLR, and with pathogenic variants. Cox proportional hazard model was used to identify the factors associated with MACEs.The median follow-up duration was 12.6 years (interquartile range: 9.5-17.9 years). Altogether, 777 patients had FH mutation and 273 had pathogenic mutation, with 92 having VUS. Over the follow-up duration, 175 MACEs were observed. LDL cholesterol level was found to be significantly higher in patients with pathogenic variants (251 mg/dL) than in patients with VUS (225 mg/dL) and without variants (203 mg/dL). Pathogenic variants and VUS are significantly associated with MACEs (hazard ratio [HR] = 1.52, 95% confidence interval [CI] = 1.02-2.02, P = 0.033 and HR = 3.18, 95% CI = 2.00-4.36, P = 1.9 × 10-5, relative to patients without any variants, respectively), independent of classical risk factors.VUS of LDLR was significantly associated with poor outcomes in FH patients. Genetic testing is useful for the diagnosis and risk stratification of FH patients.