Hypobetalipoproteinemia

Definition

A group of rare hypolipidemias characterized by permanently low plasma levels (below the 5th percentile) of total cholesterol, low density lipoprotein cholesterol and apolipoprotein B. Patients may present with malnutrition, growth delay/failure, fat malabsorption, diarrhea with steatorrhea, low levels/deficiency of liposoluble vitamins A, E, and K, hepatic complications (typically hepatomegaly with steatosis, sometimes cirrhosis), neurological (such as spastic ataxia), neuromuscular and ophthalmologic manifestations including atypical retinitis pigmentosa. Diseases in this group progress more severely when they manifest in early childhood. However, benign hypobetalipoproteinemia is generally asymptomatic and occasionally associated with dietary intolerance to fat, steatorrhea after oral intake of lipids, moderate cytolysis, cholelithiasis, moderately low levels of liposoluble vitamins and acanthocytosis in adults. Moderate hepatic steatosis and paresthesia of the extremities are sometimes observed.