VDR and alopecia: However, the mineral and skeletal phenotype of Cyp27b1 knockout mice is more severe than that of Vdr knockout (Vdr−/−) mice and cannot be fully rescued by a diet high in calcium, phosphate, and lactose.5–10 In mice and humans, functional mutations in CYP27B1 do not result in alopecia, while VDR mutations that disrupt its DNA binding do cause alopecia that is not reversed or prevented by a diet high in calcium, phosphate, and lactose.