Over three-quarters (82.7%) of people with CKD and microcytic anaemia (Hb ≤ 11 g/dl) have a ferritin less than 100 ug/mL (Chi-square, p = 0.017), compared with 58.8% of those with normocytic (Chi-square p < 0.001) and 45.5% of those with macrocytic anaemia (Chi-square p = 0.8, n.s.). The gene discussed is GSTM1; the disease is chronic kidney disease.