GSTM1 and chronic kidney disease: Numerically lower mean scores, indicating poorer HRQoL, were reported by patients with lower Hb levels for the KDQOL-36 SF-12 PCS, SF-12 MCS, symptoms and problems with kidney disease subscale, effects of kidney disease on daily life subscale, and burden of kidney disease subscale across all CKD stages, with the exception of stage 3a (Table 3).