Step 1: get the file
Log in to your 23andMe account and download your raw genotype data from the account's data download section. The file is a text file. 23andMe may ask you to confirm by email first, and the file is for you only. Do not upload it anywhere you do not trust.
Step 2: find the two variants
Open the file in a text editor or spreadsheet and search for these two rs numbers:
- rs429358
- rs7412
Each line shows the variant, the chromosome (19), the position and your two letters, for example CT. If a variant is not in your file, the chip that tested you did not include it. These two variants are absent from many commercial genotyping arrays, which is why they are sometimes tested separately (Radmanesh, 2014). Check both before you conclude anything.
Step 3: read the pair
The three common APOE versions come from the letters at the two variants (Radmanesh, 2014):
| APOE allele | rs429358 | rs7412 |
|---|---|---|
| ε2 | T | T |
| ε3 | T | C |
| ε4 | C | C |
Your file gives two letters at each variant. Combine them:
| rs429358 | rs7412 | Genotype | Copies of APOE4 |
|---|---|---|---|
| TT | CC | 3/3 | 0 |
| TT | CT | 2/3 | 0 |
| TT | TT | 2/2 | 0 |
| CT | CC | 3/4 | 1 |
| CC | CC | 4/4 | 2 |
| CT | CT | 2/4 (most likely) | 1 |
The CT / CT row is the tricky one. A file lists each variant's two letters without saying which chromosome each letter sits on. CT at both variants is most often 2/4, but the data cannot prove it. Other combinations, such as CC with CT, or CT with TT, point to rare alleles and need clinical testing to read. Do not guess.
Step 4: confirm before you act
Raw consumer data can contain errors. A study of 49 people who sent their raw-data variants for confirmation found that 40% of variants in a range of genes were false positives (Tandy-Connor, 2018). That study did not look at APOE, so it cannot tell you how often APOE is wrong. The lesson is the same: if you are going to make decisions on the result, such as changing your protocol, telling your family or discussing it with your doctor as a diagnosis, confirm it with a clinical-grade APOE test.
APOE4 is a risk factor, not a diagnosis. Phoenix explains what each genotype means: APOE 3/4, your result: one clear next step, and the risk by age page.
What to do next
- Confirm it. Ask your doctor, or order a clinical-grade APOE test. The genetic testing and family guide compares options.
- Bring it to someone who knows APOE4. Phoenix lists doctors who understand APOE4.
- Start with one step. The first 7 days guide is free.
- Join carriers who have done this. 750+ APOE4 carriers use Phoenix to turn a result like this into their own numbers. Apply to join Phoenix (60-day money-back guarantee).