Use of Uridine Triacetate to Reverse Severe Persistent Myelosuppression Following 5-fluorouracil Exposure in a Patient With a c.557A>G Heterozygous DPYD Variant

•Delayed severe toxicities can occur after fluoropyrimidine exposure in patients with heterozygous DPYD mutation genotypes, especially with DPD c.557A>G (p.Y186C) variant in patients of African descent and female sex.•Uridine triacetate treatment should not be limited to patients with early-onset fluoropyrimidine toxicities or homozygous DPYD mutations.