A low-frequency APOB p.(Pro955Ser) variant contributes to the severity of/variability in familial hypercholesterolemia.

The low-frequency APOB c.2863C > T:p.(Pro955Ser) variant is not an FH-causative variant, but it has a moderate effect size in HeFH. These findings suggest that the combination of the APOB c.2863C > T:p.(Pro955Ser) variant and age, environmental factors or other genetic factors contributes to the severity of or variability in the HeFH phenotype.