Our findings from the univariate analyses suggest that patients with ERCC2 rs13181 T/G and/or CYP3A4 rs2740574 A/G genotypes are more likely to develop grades III–IV alopecia; patients with ERCC2 rs238406 C/C genotype may develop severe leukopenia; and patients with GSTT1-null genotype could develop lymphocytopenia. The gene discussed is CYP3A4; the disease is Decreased total leukocyte count.