Hypobetalipoproteinemias (HBLs) encompass a diverse range of disorders that are characterized by reduced levels of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and apolipoprotein B (apoB) in the blood, which fall below the 5th percentile of the population distribution (1). The gene discussed is APOB; the disease is hypobetalipoproteinemia.