Individuals with this condition may develop life-threatening toxicity following exposure to 5-fluorouracil (5-FU), a chemotherapy drug that is used in the treatment of cancer.

[2][3] Beside 5-FU, widely prescribed oral fluoropyrimidine capecitabine (Xeloda) could put DPD-deficient patients at risk of experiencing severe or lethal toxicities as well.

[citation needed] A small number of genetic variants have been repeatedly associated with DPD deficiency, such as IVS14+1G>A mutation in intron 14 coupled with exon 14 deletion (a.k.a.

The Clinical Pharmacogenetics Implementation Consortium (CPIC) has issued guidelines supporting 50% dose reduction in heterozygous carriers of the decreased function variants rs3918290 (c.1905+1G>A), rs55886062 (c.1679T>G), rs56038477(c.1236G>A), rs67376798 (c.2846A>T), c.2846A>T (rs67376798) or c.1129–5923C>G (rs75017182; HapB3 or its tagging SNP c.1236G>A; rs56038477) [6] Although DPYD pre-treatment screening has been proven to improve drug safety for DPYD*2A carriers by the Food and Drug Administration, the current (version 2016) European Society for Medical Oncology (ESMO) guidelines do not “routinely recommend” upfront genotyping of DPYD*2A before the administration of 5‐FU in metastatic CRC (mCRC) patients.

Instead, on April 30, 2020, the European Society for Medical Oncology issued a document recommending genetic testing.