The serum 24,25OH2D level was lower in adult patients with chronic kidney disease, which was suggestive of decreases in vitamin D catabolism and VDR activity, and reduced 1,25OH2D production, the level of which better correlated with the serum PTH level than did either the 25OHD or 1,25OH2D level [48]. The gene discussed is PTH; the disease is chronic kidney disease.