Phenotypic and Genetic Analyses of Korean Patients with Familial Hypercholesterolemia: Results from the KFH Registry 2020

Aims: Familial hypercholesterolemia (FH) is currently a worldwide health issue. Understanding the characteristics of patients is important for proper diagnosis and treatment. This study aimed to analyze the phenotypic and genetic features, including threshold cholesterol levels, of Korean patients with FH. Methods: A total of 296 patients enrolled in the Korean FH registry were included, according to the following criteria: low-density lipoprotein-cholesterol (LDL-C) ＞190 mg/dL with tendon xanthoma or family history compatible with FH, or LDL-C ＞225 mg/dL. DNA sequences of three FH-associated genes were obtained using whole-exome or target exome sequencing. Threshold cholesterol levels for differentiating patients with FH/ pathogenic variant (PV) carriers and predictors of PVs were identified. Results: Of the 296 patients, 104 had PVs and showed more obvious clinical findings, including higher cholesterol levels. PV rates ranged from 30% to 64% when patients were categorized by possible or definite type according to the Simon Broome criteria. Frequent PV types included missense variants and copy number variations (CNVs), while the most frequent location of PVs was p.P685L in LDLR. The threshold LDL-C levels for patient differentiation and PV prediction were 177 and 225 mg/dL, respectively. Younger age, tendon xanthoma, and higher LDL-C levels were identified as independent predictors of PVs, while traditional cardiovascular risk factors were predictors of coronary artery disease. Conclusions: Korean patients with FH had variable PV rates depending on diagnostic criteria and distinctive PV locations. The reported threshold LDL-C levels pave the way for efficient patient care in this population.