DPYD and dihydropyrimidine dehydrogenase deficiency: The extra variants assessed were four common variants (rs12132152 and rs12022243 in DPYD [9], rs2612091 in ENOSF1 [9] and MIR27a variant rs895819 [17]) which met inclusion criteria 1 and 14 DPYD deficiency/no function alleles which met inclusion criteria 2 (Table S1).