Since CKD is associated with klotho and human CAVD (28) and the AV calcification in Kl–/– mice resembles human CAVD (29), the Kl–/– mice are useful mouse models for investigating the mechanisms involved in pathogenesis of CAVD (29, 30). The gene discussed is KL; the disease is congenital bilateral aplasia of vas deferens from CFTR mutation.