Heterozygous Familial Hypercholesterolemia (HeFH) is a severe autosomal dominant disease which is under-diagnosed. The prevalence of HeFH has rarely been assessed in an unselected sample from the general population.

Based on a huge sample of lipid panels, we assessed the prevalence of individuals classified with definite or probable HeFH (Dutch Lipid Clinic Network (DLCN) criteria)>5 that is to say LDL-cholesterol (LDL-C)>6.5mmol/L (251mg/dL). From 2006 to 2015, 200 620 LDL-C were obtained from 105 398 subjects in a large database of a French University Hospital. Subjects from 0 to 102 years (53.7±20.5) and of both genders were analysed. LDL-C levels were calculated with the Friedewald or the Planella formula if elevated triglycerides. We also assessed the prevalence of all DLCN LDL-C criteria: 4.0-4.9mmol/L (155-190mg/dL); 5.0-6.4mmol/L (191-250mg/dL); 6.5-8.4mmol/L (251-325mg/dL);>8.5mmol/L (>325mg/dL).

The prevalence of LDL-C between 4.0 and 4.9mmol/L was 9.81% [95% CI: 9.68-9.94]; the prevalence of LDL-C between 5.0 and 6.4mmol/L was 2.41% [95% CI: 2.35-2.48]; the prevalence of LDL-C between 6.5 and 8.4mmol/L was 0.37% [95% CI: 0.34-0.39] and the prevalence of LDL-C>8.5mmol/L was 0.09% [95% CI: 0.08-0.10]. In the first lipid determinations of 105 398 subjects, the prevalence of LDL-C between 4.0 and 4.9mmol/L was 10.77% [95% CI: 10.6-11.0]; between 5.0 and 6.4mmol/L was 2.47% [95% CI: 2.38-2.56]; between 6.5 and 8.4mmol/L was 0.28% [95% CI: 0.25-0.32] and of LDL-C>8.5mmol/L was 0.06% [95% CI: 0.04-0.07]. The prevalence of definite or probable HeFH was 0.46% in 200 620 lipid determinations and 0.34% in 105 398 subjects. The highest prevalence of definite or probable HeFH was in subjects aged between 35 and 55 years.

In France, the prevalence of definite or probable HeFH was 1/250 adults, very closed to the observed prevalence of 1/200 obtained in the Copenhagen General Population Study.