CKD patients have low levels of 25-hydroxyvitamin D (25 vitamin D), but also lack the physiological capacity to hydroxylate 25 vitamin D into its active form 1,25-dihydroxyvitamin D (1,25 vitamin D), which binds to the vitamin D receptors (VDR) found in blood vessels, the heart, muscles and kidneys. This evidence concerns the gene VDR and chronic kidney disease.