It has been well documented that 1,25(OH)2-D increases plasma FGF23 concentrations in both rodents [59] and humans with preserved renal function [60], and the so-called active vitamin D analogues (e.g., doxecalciferol) increase the plasma concentrations of FGF23 in peritoneal dialysis patients with secondary hyperparathyroidism (sHPT) [61]. The gene discussed is FGF23; the disease is secondary hyperparathyroidism.