CYP27A1 and Obesity: Obesity has previously been linked to altered expression of Cyp27A1 in mice, in a tissue-specific manner: in male C57BL/6 mice fed a high-fat diet, hepatic expression of Cyp27A1 were found to be lower than in control mice, while the reverse was true in visceral adipose tissue, and has been associated with changes in vitamin D metabolism [51].