Notable SNPs associated with elevated incidence and severity of neutropenia include those in the ABCB1 [35,67,68,69,70], UGT1A1 [71,72,73], ERCC1 [35,69], TP53 [74,75], MDM2 [74,75], and SLCO1B1 [73,76] genes (Figure 3). This evidence concerns the gene ABCB1 and Decreased total neutrophil count.