The average self-reported sun exposure was similar in both groups and the intestinal involvement and renal insufficiency are not likely the cause of the low vitamin D level; in fact, all our patients showed normal value of prothrombin time and normal value of blood urea nitrogen and creatinine levels which allows to exclude an overt malabsorbiment of liposoluble vitamins and renal insufficiency. The gene discussed is F2; the disease is Renal insufficiency.