Patients bearing DPYD c.1905+1G/A or DPYD c.2846A/T variants (n = 10) had an increased risk of experiencing grade ≥ 3 overall hematological AEs (OR, 3.88 [95% CI, 0.99–15.23]; P = 0.05), neutropenia (OR, 4.12 [95% CI, 1.05–16.17]; P = 0.04), thrombocytopenia (OR, 9.42 [95% CI, 1.00–89.06]; P = 0.05) and stomatitis (OR, 10.33 [95% CI, 2.74–38.91]; P < 0.001), as compared to patients bearing DPYD c.1905+1G/G and DPYD c.2846A/A genotypes (n = 429) (Supplementary Table 4). The gene discussed is DPYD; the disease is stomatitis.