APOB (apolipoprotein B) is a structural component of lipoproteins with a functional role as a ligand that binds to cell-surface receptors, including the LDL (low-density lipoprotein) receptor.1 Rare protein-truncating variants (PTVs) that truncate APOB lead to familial hypobetalipoproteinemia (FHBL, OMIM no. 107730), an autosomal dominant genetic disorder characterized by low levels of plasma LDL-C (LDL cholesterol).2,3 Those affected by FHBL display not only lower LDL-C but also nonalcoholic fatty liver disease. Here, APOB is linked to familial hypobetalipoproteinemia 1.