DPYD*2A — fluoropyrimidine toxicity risk
One copy of the DPYD*2A loss-of-function variant detected.
You have one working copy and one non-working copy of the DPYD gene.
Intermediate DPD enzyme activity. Standard doses of fluorouracil or capecitabine can cause severe toxicity; substantial dose reduction (often by half) is recommended if these chemotherapies are prescribed.
Two common chemotherapy drugs (fluorouracil and capecitabine) can cause severe side effects at standard doses for you, because your body breaks them down too slowly. If you ever need them, oncologists typically halve the dose. Crucial information to share before any cancer treatment.
What this means
DPYD encodes dihydropyrimidine dehydrogenase, the rate-limiting enzyme in fluorouracil (5-FU) and capecitabine metabolism. These are mainstay chemotherapies for colorectal, breast, and other cancers. DPD-deficient patients can suffer fatal toxicity at standard doses. Pre-treatment DPYD genotyping is now standard practice in much of Europe and increasingly in the US, and *2A is one of four widely-tested variants.
DPYD makes an enzyme that breaks down two widely-used chemotherapy drugs: fluorouracil (5-FU) and capecitabine. They're standard treatments for colorectal, breast, and several other cancers. If your DPYD doesn't work properly, the chemo isn't cleared from your body in time and can build up to dangerous — sometimes fatal — levels at standard doses. Checking this gene before starting these chemotherapies is now standard practice in much of Europe and increasingly in the US. *2A is one of four versions that clinicians routinely look for. Outside of cancer treatment, this finding doesn't affect everyday medicines.
Caveats
- This finding only matters if fluorouracil or capecitabine is ever prescribed; please mention it to your oncologist before starting any chemotherapy.
- DPYD also matters for some topical 5-FU and the antifungal flucytosine.
- Other DPYD variants exist; this is one of several tested clinically.