Table 4.

Allelic Phenotypes

GenePhenotypePathogenic VariantsClinical Characteristics
APOB APOB-related familial hypobetalipoproteinemia Typically truncating biallelic or heterozygous variants
  • Homozygous: hepatomegaly, steatorrhea, growth deficiency, deficiency of fat-soluble vitamins, GI, & neurologic dysfunction; plasma total cholesterol, LDL-C, & apo B levels typically <5% for age & sex
  • Heterozygous: possible risk of liver dysfunction & hepatic steatosis; rarely (~5%-10% of persons), severe nonalcoholic steatosis → cirrhosis
PCSK9 Hypocholesterolemia w/↓ LDL cholesterol (OMIM 603776)Loss-of-function variants↑ LDL receptors on surface of liver cells, ↑ removal of LDL-C from blood (& therefore ↓ LDL-C levels) & ↓ risk for CAD.

CAD = coronary artery disease; GI = gastrointestinal

From: Familial Hypercholesterolemia

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