APOE Genotyping
Purpose
The test detects the three most common APOE alleles e2, e3, and e4 that encode APOE isoforms E2, E3, and E4 respectively, with two separate allelic discrimination assays for single nucleotide variants at APOE codons 130 (rs429358) and 178 (rs7412), each utilizing allele-specific hydrolysis probes. APOE genotyping is primarily used to assess risk for amyloid related imaging abnormalities in individuals being treated for Alzheimer Disease (AD) with B-amyloid-targeting antibodies. APOE e4 homozygosity is associated with an increased risk for these abnormalities. Treatment is NOT contraindicated in these individuals, but they may undergo closer monitoring for the abnormalities during treatment. APOE 44 homozygosity may increase the risk for AD in individuals not yet diagnosed with the condition. Although not recommended for this use, clinicians may decide, in specific instances, following genetic counseling, to assess patient risk by testing for APOE e4.
CPT Code
81401
Methodology
Real-time PCR w/ allele-specific probes
Turnaround Time
14 days
Specimen
Blood in EDTA, buccal swab