Homozygous Familial Hypercholesterolemia: Genetic Abnormalities | Patient Case Quiz

A 37-year-old Caucasian man presents to clinic to establish care. At age 18 years, he was diagnosed with homozygous familial hypercholesterolemia (HoFH) after his father died suddenly of a massive myocardial infarction at age 42 years. Two paternal uncles also died suddenly at ages 39 and 45 years. At that time, his low-density lipoprotein cholesterol (LDL-C) was 530 mg/dL, and he was started on a statin and advised to initiate LDL-C apheresis. He notes that he stopped the statin after seven months because "he did not like the way it made him feel." He also discontinued apheresis because it required a 3.5-hour drive each way to reach an academic medical center, and his health insurance only covered approximately 30% of the cost. Despite much encouragement, he rejected the possibility of liver transplantation. He stopped following up with a physician. At age 35 years, he sustained an inferior wall myocardial infarction. On cardiac catheterization, he was found to have diffuse multivessel disease with an 80% obstruction in his left main coronary artery, a 75% obstruction in his proximal circumflex artery, and a completely occluded right coronary artery at approximately the middle portion of the vessel. He underwent a three-vessel coronary artery bypass without complication.

FH can be attributed to abnormalities in which of the following?

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