The CANDLE-KIT study (Correcting Anemia and Native Vitamin D Supplementation in Kidney Transplant Recipients; ClinicalTrials.gov Identifier: NCT01817699) is another open-label RCT with four arms: 1) no intervention: low haemoglobin (Hb) target (Hb level: ≥9.5 and <10.5 g/dL) without cholecalciferol; 2) low Hb target with cholecalciferol 1,000 IU/day; 3) high Hb target (Hb level: ≥12.5 and <13.5 g/dL) without cholecalciferol, and 4) the experimental arm: high Hb target with cholecalciferol 1,000 IU/day. Here, GSTM1 is linked to anemia (phenotype).