The elevated circulating 1,25-dihydroxyvitamin D3 concentrations observed in the Trpv5682P/682P mice indicate that the mild asymptomatic hypocalcaemia, despite the severe renal loss of calcium in these mutant mice, is being maintained via a compensatory, 1,25-dihydroxyvitamin D3 mediated increase in intestinal calcium absorption, as reported in Trpv5-/- mice [25]. This evidence concerns the gene TRPV5 and Hypocalcemia.