GSTM1 and chronic kidney disease: The prevalence of anemia in CKD in more recent references from Japan is estimated at 40.1% in stage G4 and 60.3% in stage G5 [9]; anemia prevalence (Hb < 10 g/dL) in a cohort of 5 million patients in the US with GFR < 74 mL/min is estimated at 59% in men and 71.4% in women [10].