Issues

The cover image is adapted from Figure 1 in the article, “Genetic factors associated with absolute and relative plasma concentrations of calcitrio”l, by Wilson and colleagues. Figure 1 shows a Concordance Correlation Coefficient (CCC) Plot comparing the calcitriol-24,25-dihydroxyvitamin D₃-calcifediol proportion ratio (C24CPR) to the crude 1,25(OH)₂D₃ to 24,25(OH)₂D₃ concentration ratio. The purpose of this study was to investigate genetic factors associated with plasma 1,25(OH)₂D₃ and a relative measure of plasma 1,25(OH)₂D₃—the calcitriol-24,25-dihydroxyvitamin D₃-calcifediol proportion ratio (C24CPR) among healthy individuals. Because circulating vitamin D5 metabolite concentrations are known to differ to the greatest extent between individuals of African and European ancestry, the authors focused this study on healthy individuals from these racial/ethnic groups. Using a cross-sectional study design, healthy young adults of African and European descent, matched (1:1) on age (+/− 5 years) provided a blood sample in non-summer months. Both absolute and relative measures of calcitriol were significantly higher among African Americans. Otherwise, these biomarkers appear to be genetically distinct. C24CPR may be better suited to personalized medicine, due to a higher proportion of population variability explained by genetic variation and a less skewed distribution. For more information, see the article beginning on page 697.