The key players of CKD-MBD, calcium, phosphate, parathormone (PTH), fibroblast growth factor 23 (FGF23), and the vitamin D hormonal system are adversely affected by the deterioration of kidney function, which deregulates the tightly interrelated mechanisms that control these parameters [77]. The gene discussed is FGF23; the disease is Marchiafava-Bignami disease.