Hypobetalipoproteinaemia secondary to chronic hepatitis C virus infection in a patient with familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is a common genetic disorder characterized by high plasma low-density lipoprotein (LDL)-cholesterol and premature coronary artery disease. Many factors, such as illness, high-dose statin therapy or a strict vegan diet can cause hypobetalipoproteinaemia (HBL). The more common secondary causes of HBL in the hospital setting include cachexia, intestinal malabsorption, malnutrition, severe liver disease and hyperthyroidism. We report a case of HBL in a 43-year-old man with previously demonstrated marked hypercholesterolaemia who attended a lipid disorders clinic for FH cascade screening. Surprisingly, a lipid profile taken at that time showed low plasma LDL-cholesterol and apolipoprotein B concentrations of 1.6 mmol/L and 0.61 g/L, respectively. He was not on lipid-lowering therapy. DNA sequencing showed that he was heterozygous for the LDLR gene mutation (C677R) present in other affected family members. Of interest, his serum transaminases were increased by ∼3-fold and hepatitis serology and genotyping confirmed a diagnosis of hepatitis C virus (HCV) infection. In summary, we describe a case of HBL secondary to chronic HCV infection in a patient with FH, confirmed by mutational analysis.