MTHFR and chronic kidney disease: Finally, associations with classical CKD biochemical parameters were found for creatinine (GPX1, GSTO1, GSTO2, KL, MGP), glomerular filtration rate (GPX1, GSTO1, KL, ICAM-1, MGP), hemoglobin (ERCC2, SHROOM3), resistance index erythropoietin (SOD2, VEGFA, MTHFR, KL), albumin (SOD1, SOD2, GSTO2, ERCC2), phosphorus (IL-4, ERCC4, SOD1, GPX1, GPX4) parathyroid hormone (IL-1A, IL6, SHROOM3, UMOD, ICAM-1), C-reactive protein (SOD2, GSTP1, XRCC1), and ferritin (SOD2, GSTP1, SLC7A9, GPX4).