Apolipoprotein E is present on chylomicrons, VLDLs, and HDLs and functions as a ligand for lipoprotein receptors. The apoE gene has three common alleles (E2, E3, E4) that code for three isoforms of the apoE protein (E2, E3, E4). The alleles are inherited in a co-dominant manner resulting in six genotypes (e2/e2, e2/e3, e2/e4, e3/e3, e3/e4, e4/e4).

Clinical Implications:

Individuals who are e2/e2 are prone to develop Type III hyperlipidemia. The E4 allele is associated with increased plasma cholesterol levels and subsequent increased risk for coronary heart disease. ApoE genotype can play a significant role in predicting patient responsiveness to cardiac-related environmental factors, statin therapy, and dietary therapy.

Treatment considerations:

Compared to "standard" treatment recommendations for the "normal" apo E3 patients, and considering associated cardiovascular disease risk marker abnormalities, personalized recommendations for lifestyle changes and pharmacotherapy may be modified with apo E2 and apo E4 genotype patients.

• Apo E2:
  • Low fat diet may increase small dense LDL
  • Moderate (35%) fat dietary restriction recommended
• Apo E3:
  • Normal treatment guideline recommendations
  • Preventive (25%) fat or moderate (35%) fat dietary restriction determined by overall lipid profile
• Apo E4:
  • Very low (20%) fat dietary restriction recommended

Due to the unique nature of genetic testing, physicians may suggest patients consider genetic counseling. Informed consent is recommended and required for patients according to state law. Consent forms are available from Berkeley HeartLab, Inc upon request.