DPYD and dihydropyrimidine dehydrogenase deficiency: Lastly, three patients had fasting pretreatment plasma uracil concentrations of ≥ 16 ng/mL without carrying a canonically deleterious mutation in DPYD. One of these patients carried a novel and likely deleterious DPYD gene variant (c.2185G > A [p.A729T]), while the other two patients did not have genetic or clinical evidence of DPD deficiency.