KL and chronic kidney disease: The levels of Klotho in the blood and urine of chronic kidney disease (CKD) patients are significantly reduced compared with the general population, and CKD patients have a high incidence of vascular calcification [2]. Klotho gene knockdown mice show obvious vascular calcification and premature aging [3], and the overexpression of the Klotho gene in mice has the completely opposite results [4].