Familial hypobetalipoproteinaemia: a rare presentation to the lipid clinic

To report a case of familial hypobetalipoproteinaemia in a woman who presented after the incidental finding of marked hypocholesterolaemia during laboratory tests.

An asymptomatic 37-year-old Lebanese woman presented to the lipid clinic with a serum total cholesterol concentration of 1.1 mmol/L, high density lipoprotein (HDL) cholesterol of 1.0 mmol/L, and triglycerides of 0.28 mmol/L. No secondary cause for the hypocholesterolaemia was established. INVESTIGATION AND OUTCOME: Her serum apolipoprotein B (apo B) levels were markedly reduced at 0.07 g/L. Except for one daughter (IV-4), all other family members including her husband (her first cousin) had apo B levels about 25% of normal. Daughter IV-4 had undetectable apo B levels. Family studies confirmed an autosomal dominant pattern of inheritance consistent with familial hypobetalipoproteinaemia.

Familial hypobetalipoproteinaemia is a rare condition that should be considered in the differential diagnosis of hypocholesterolaemia. Absence of clinical features, autosomal dominant pattern of inheritance, and reduced apo B levels suggest the diagnosis.