rs3918290
A SNP in the DPYD gene on chromosome 1. Its most notable genotype is T;T: 5-fluorouracil toxicity, dihydropyrimidine dehydrogenase deficiency
- Gene
- DPYD
- Location
- Chr 197,450,058 (GRCh38)
- Highest magnitude
- 3.5Important
- Tested on
- 23andMe, AncestryDNA, FamilyTreeDNA
- Minor allele frequency
- <1%
Genotypes
Plus strand, as in 23andMe and AncestryDNA files.
- T;TMost notableBad5-fluorouracil toxicity, dihydropyrimidine dehydrogenase deficiency
- C;TBadsome 5-fluorouracil toxicity, dihydropyrimidine dehydrogenase deficiency carrier
- C;CGoodcommon in complete genomics
SNPedia records rs3918290 on the minus strand: (A;A), (A;G), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.
Frequency
Share of each genotype in 7 HapMap populations.
- AverageT;T 0% C;T <1% C;C 99%
- European ancestry (Utah)T;T 0% C;T <1% C;C 99%
- Han Chinese (Beijing)T;T 0% C;T 0% C;C 100%
- Japanese (Tokyo)T;T 0% C;T 0% C;C 100%
- Yoruba (Nigeria)T;T 0% C;T 0% C;C 100%
- African ancestry (Southwest US)T;T 0% C;T 2% C;C 98%
- Gujarati IndianT;T 0% C;T 3% C;C 97%
- TuscanT;T 0% C;T 1% C;C 99%
Related
Conditions, medicines and genes
Other DPYD SNPs
Genosets
- Gs306Poor metabolizer of fluoropyrimidines (e.g. 5-fluorouracil, capecitabine or tegafur).Very important
- Gs312Intermediate metabolizer of fluoropyrimidines (such as 5-fluorouracil and capecitabine).Very important
- Gs313Normal DPYD activity and thus 5-FU metabolism predicted, since none of the three best described nonfunctional DPYD alleles were observed.Worth knowing
Genosets combine several genotypes. Twofold checks them in your report.
Notes
From SNPedia
Show notes, about 130 words
23andMe reports that the A allele of rs3918290 is associated with the rare recessive disorder dihydropyrimidine dehydrogenase deficiency (DPD), also known as hereditary thymine-uraciluria or familial pyrimidinemia. Note that the terms used in the literature for this gene can be confusing, since the gene is in reverse orientation to the chromosome strand on the reference genome. pharmgkb - defines *2A allele, which has a significantly higher chance of 5-fluorouracil toxicity Fluorouracil Toxicity
T;T
You can expect toxicity from 5-fluorouracil, a common treatment for various cancers. This variation does not influence your risk of cancer.
C;T
You can expect some toxicity from 5-fluorouracil, a common treatment for various cancers. This variation does not influence your risk of cancer.
Source and license
Adapted from rs3918290 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.
SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.