SFRP5 and chronic kidney disease: DNA methylation of genes is linked with CKD and renal fibrosis, including PTPN6, CEBPB, EBF1, Klotho (Chu et al., 2017; Yin et al., 2017), SMAD7 (Yang et al., 2020), sFRP5 (Yu et al., 2017), and RASAL1. Notably, DNA methylation inhibits erythropoietin expression, causing anemia, a prevalent complication of CKD (Yin and Blanchard, 2000).