A comparison of GSTM1 null gene polymorphism in the group of children with leukopenia also found to be significantly decreased WBC (p = 0.0001), neutrophil (p = 0.0001), basophil (p = 0.0449), lymphocyte (p = 0.0001), and monocyte (p = 0.0014) counts (Table 4). The gene discussed is GSTM1; the disease is Decreased total leukocyte count.