Tuberculosis and chronic hepatitis B virus infection in Africans and variation in the vitamin D receptor gene

The active metabolite of vitamin D, 1,25 dihydroxyvitamin D3, is an importa nt immunoregulatory hormone [1], Its effects are exerted by interaction wit h the vitamin D receptor, which is present on human monocytes and activated T and B lymphocytes, Variation in the vitamin D receptor gene was typed in 2015 subjects from large case-control studies of three major infectious di seases: tuberculosis, malaria, and hepatitis B virus, Homozygotes for a pol ymorphism at codon 352 (genotype tt) were significantly underrepresented am ong those with tuberculosis (chi(2) = 6.22, 1 df, P = .01) and persistent h epatitis B infection (chi(2) = 6.25, 1 df, P = .01) but not in subjects wit h clinical malaria compared with the other genotypes, Therefore, this genet ic variant, which predisposes to low bone mineral density in many populatio ns, may confer resistance to certain infectious diseases.