ApoE is a critical protein component of very low-density lipoprotein (VLDL) and chylomicrons. ApoE is important for:

Cholesterol absorption from the intestine

Uptake of triglyceride-rich lipoproteins by the liver

The intended use of apoE genetic testing is as an aid in the selection of optimal cholesterol-lowering protocols by the healthcare provider. The genetic test identifies individuals with altered lipid transport. Depending on the apoE genotype, cholesterol-lowering dietary interventions are very effective in these individuals, so the determination of the genotype allows the physician to select the most efficacious treatment regimen for the patient for lowering low-density lipoprotein cholesterol and reducing heart disease risk.

The APOE gene has three common alleles (E2, E3, E4) that encode for three protein isoforms (E2, E3, E4). ApoE3 is the most common form of apoE. Population frequencies for these apoE alleles are: E2 (15%) E3 (65%) E4 (20%)

• E3/E3
  Most common genotype; associated with:1-2
  • Decreased uptake of cholesterol by the liver
  • Lower total cholesterol and LDL-C
• E2/E2, E2/E3
  Associated with:1-2
  • Lower LDL-C levels than the common E3/E3 genotype
  • Lower total cholesterol and LDL-CV
• E4/E4, E3/E4
  Associated with higher LDL-C levels than the common E3/E3 genotype. Also associated with increased:1-2
  • Cholesterol absorption in the intestine
  • Uptake of intestinal cholesterol by the liver
  • Total cholesterol and LDL-C
• References:
• 1. Wilson PWF, Myers RH, Larson MG, Ordovas JM, Wolf PA, Schaefer EJ. Apolipoprotein E alleles, dyslipidemia, and coronary heart disease: the Framingham Off spring Study. JAMA. 1994;272(21):1666-1671.
• 2. Bennet AM, Di Angelantonio E, Ye Z, et al. Association of apolipoprotein E genotypes with lipid levels and coronary risk. JAMA. 2007;298(11):1300-1311.

Methodology - Real-time polymerase chain reaction (PCR)