Prevalence and clinical correlates of familial hypercholesterolemia founder mutations in the general population

Objective: This study aimed to investigate the exact prevalence of familial hypercholesterolemia (FH) in the general population, taking advantage of the fact that five low-density lipoprotein receptor (LDLR) founder mutations account for 78% of FH cases in Finland. Methods: Five LDLR founder mutations, FH-North Karelia, FH-Helsinki, FH-Pogosta, FH-Turku, and FH-Pori, were genotyped and serum lipid levels were measured in a large collection of Finnish population cohorts (n = 28,465), including the National FINRISK Study and the Health 2000 Study. Follow-up data were obtained from national healthcare registries. Results: The combined prevalence of three of the five FH founder mutations (FH-North Karelia, FH-Helsinki, and FH-Pogosta) was 0.12% (95% CI 0.07-0.16%), while FH-Turku and FH-Pori were not identified in the present sample cohort. Our data suggest that the estimated total prevalence of FH in Finland is at least 0.17%. Approximately half of the 35 FH mutation carriers used lipid-lowering medication at the time of the baseline investigation. LDL cholesterol levels were on average 2 mmol/L higher in mutation carriers than in non-carriers (p < 0.001) but did not differ between FH mutation carriers with and without lipid-lowering medication. During the follow-up for 13 years, one mutation carrier encountered a probable sudden cardiac death, two mutation carriers suffered from a stroke, and one from a myocardial infarction. Conclusions: In Finland, at least 1 in 600 individuals is estimated to have FH. A marked undertreatment of FH was observed in LDLR mutation carriers.