PCSK9 and familial hypercholesterolemia: A study of 138 individuals with heterozygous familial hypercholesterolemia (HeFH) and CAD found significantly higher levels of mature PCSK9 than fc-PCSK9, and fc-PCSK9 was not associated with any intravascular ultrasound measures (including percent atheroma volume, blood vessel volume, and lumen volume) with adjustment for age, sex, other clinical characteristics, and blood biomarkers [52] (Table 2).