Van Erp et al. observed an increased risk for leukopenia in CYP1A1 rs1048943 and FLT3 rs1933437 and an absence of CAG in the NR1/3 haplotype (rs2307424, rs2307418, rs4073054); CYP1A1 rs1048943 was associated with mucosal inflammation; and EGFR2 rs2305948 was associated with any toxicity > grade 2 (van Erp et al., 2009). The gene discussed is CYP1A1; the disease is Decreased total leukocyte count.