Vitamin D receptor polymorphisms and nutritional rickets in Nigerian children

Nutritional rickets is common in Nigeria where vitamin D deficiency is rare and dietary insufficiency of calcium is common. It occurs more commonly in siblings of affected children than of unaffected children. Postulating tha t vitamin D receptor (VDR) polymorphisms might relate to the susceptibility of some Nigerian children to develop rickets in the setting of low calcium intake, we compared the VDR genotypes, as determined by the presence or ab sence of Bsm I, Apa I, Tag I, and Fok I restriction enzyme cleavage sites, between 105 children with active nutritional rickets and 94 subjects repres entative of the community from which the rachitic children came. In the ric kets group, the ff genotype was less common than in the community group, an d the FF genotype was relatively increased (f allele frequency, 17% in rach itic children and 26% in the community group, p = 0.03), Neither individual allele frequencies for the other polymorphisms nor combinations of genotyp es at different sites were different between the rachitic and community gro ups. Although it is not clear why a presumed better-functioning VDR variant (F allele) is associated with an increased risk of developing rickets, thi s study raises the possibility that VDR alleles might be important in deter mining an individual's susceptibility to developing rickets when faced with dietary calcium deficiency.