Apolipoprotein B is a major protein constituent of chylomicrons (apo B-48), LDL (apo B-100) and VLDL (apo B-100). Apo B-100 functions as a recognition signal for the cellular binding and internalization of LDL particles by the apoB/E receptor.
Hypobetalipoproteinemia, familial, 1 (FHBL1) [MIM:615558]: A disorder of lipid metabolism characterized by less than 5th percentile age- and sex-specific levels of low density lipoproteins, and dietary fat malabsorption. Clinical presentation may vary from no symptoms to severe gastrointestinal and neurological dysfunction similar to abetalipoproteinemia. Note=The disease is caused by mutations affecting the gene represented in this entry. Most cases of FHBL1 result from nonsense mutations in the APOB gene that lead to a premature stop codon, which generate prematurely truncated apo B protein products (PubMed:21981844).
Familial ligand-defective apolipoprotein B-100 (FDB) [MIM:144010]: Dominantly inherited disorder of lipoprotein metabolism leading to hypercholesterolemia and increased proneness to coronary artery disease (CAD). The plasma cholesterol levels are dramatically elevated due to impaired clearance of LDL particles by defective APOB/E receptors. Note=The disease is caused by mutations affecting the gene represented in this entry.
Note=Defects in APOB associated with defects in other genes (polygenic) can contribute to hypocholesterolemia.