ABCB1 and neutropenia: They also showed that for patients who developed neutropenia (N = 38), compared to controls (N = 241), ABCB1 3435TT and homozygosity for glutathione S-transferase theta 1 (GSTT1)null occurred more frequently, but glutathione S-transferase mu 1 (GSTM1)null occurred less frequently (van der Weide et al., 2017).