1,25(OH)2D3 and its receptor also play a pivotal role in multiple sclerosis (MS), as low levels of 1,25(OH)2D3 and the circulating form of 25-hydroxyvitamin D3 (25(OH)D3) or alterations in the VDR gene are a risk factor for this condition [27]. The gene discussed is VDR; the disease is multiple sclerosis.