Oligogenic Familial Hypercholesterolemia Treated by Combination Therapy of Statin, Ezetimibe, PCSK9 Inhibitor, and Lomitapide.

We encountered a 40-year-old man diagnosed with homozygous familial hypercholesterolemia (FH) based on clinical findings. The initial low-density lipoprotein (LDL)-cholesterol level was 393 mg/dL. He underwent coronary artery bypass graft (CABG) surgery for three-vessel disease. Genetic testing revealed a pathogenic variant in the LDL receptor (LDLR) and a missense variant in apolipoprotein E (APOE), known as APOE4, leading to the diagnosis of oligogenic FH. His LDL-cholesterol level was well controlled by the introduction of a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor and lomitapide (approximately 30 mg/dL). Combination therapy is effective in reducing LDL levels.