CYP2D6*4 — reduced metabolism of many drugs
One copy of the CYP2D6*4 loss-of-function variant detected.
You have one working copy and one non-working copy of the CYP2D6 gene.
Likely intermediate metabolizer. Affects how the body processes a long list of common drugs — codeine, tramadol, tamoxifen, many antidepressants, antipsychotics, and beta-blockers.
You process a long list of common medicines more slowly than average — including the painkillers codeine and tramadol, the breast-cancer drug tamoxifen, many antidepressants and antipsychotics, and some beta-blockers.
What this means
CYP2D6 is one of the most clinically important drug-metabolising enzymes. *4 is the most common loss-of-function allele in European populations. Pharmacogenetic guidance exists for codeine, tramadol, tamoxifen, several antidepressants, atomoxetine, and many others. CYP2D6 genotyping is complex: copy number variation matters, and tag-SNP-based inference (as on consumer chips) can miss important alleles.
CYP2D6 is one of the most important drug-processing enzymes in your liver — it breaks down a huge list of common medicines. The *4 version produces an enzyme that doesn't really work, and it's the most common non-working version in people of European descent. Medical guidelines exist for adjusting doses of codeine, tramadol, tamoxifen, several antidepressants, the ADHD drug atomoxetine, and many others based on CYP2D6 status. One thing to know: CYP2D6 is genetically complex, so a single DNA reading like this one gives a useful hint but doesn't capture the full picture — a specialist test gives more detail if a doctor needs it for prescribing.
Caveats
- CYP2D6 is one of the most variable genes in the human genome. Single-SNP inference is approximate.
- For full clinical use, a specialist pharmacogenetic test is preferable.
- The list of affected drugs is long; mention this to any new prescriber.