UGT1A9 and obesity due to melanocortin 4 receptor deficiency: From UDP-D-glucuronate to D-glucuronate, Ugt1a9 and Ugt2b1 genes are involved, the expression of Ugt1a9 and Ugt2b1 was downregulated, and the content of D-glucuronate was decreased in obese kidney, suggesting that obesity can affect ascorbate biosynthesis (Fig 7).