Common genetic polymorphisms may explain racial differences in manifestations of vitamin D deficiency, according to research published in the New England Journal of Medicine.
Camille E. Powe, M.D., of Brigham and Women’s Hospital in Boston, and colleagues analyzed blood samples and performed genotyping of DNA samples from black and white participants in a population cohort study to examine racial differences in the assessment of vitamin D status. Genotyping was done for two common polymorphisms in the D-binding protein gene (rs7041 and rs4588).
The researchers found that mean levels of total 25-hydroxyvitamin D and vitamin D-binding protein were significantly lower in blacks than in whites. Genetic polymorphisms independently seemed to explain 79.4 percent of the variation in the levels of vitamin D-binding protein and 9.9 percent of the variation in levels of 25-hydroxyvitamin D. Bone mineral density (BMD) was significantly higher in blacks than in whites. Among homozygous participants, the levels of bioavailable 25-hydroxyvitamin D overall were similar for blacks and whites.
“Community-dwelling black Americans, as compared with whites, had low levels of total 25-hydroxyvitamin D and vitamin D-binding protein, resulting in similar concentrations of estimated bioavailable 25-hydroxyvitamin D,” the authors write. “Racial differences in the prevalence of common genetic polymorphisms provide a likely explanation for this observation.”
Several authors disclosed being co-inventors on a patent pending on the use of bioavailable vitamin D for the assessment of vitamin D status.