Abstract 4481: Vitamin D pathway gene variants associated with vitamin D deficiency in African Americans

Background: Cancer incidence and mortality rate is disproportionate among the racial/ethnic groups in the U.S. and higher in African Americans (AAs) due to a combination of genes and environmental factors. The difference in serum vitamin D3, 25(OH)D, concentration among racial groups is suspected to be one of the sources of cancer health disparities. Vitamin D has protective effects against several types of cancer, and vitamin D deficiency is more common among AAs than the European Americans (EAs). Genome-Wide Association Studies (GWAS) among EAs found vitamin D pathway gene (VDPG) variants associated with serum 25(OH)D level, but association between VDPG variants and serum 25(OH)D level has not examined in AAs. Here, we tested if thirty-nine VDPG variants are associated with serum 25(OH)D concentration. Samples and Methods: Nineteen variants in GC, VDR, CYP3A4, CYP2R1, and CYP24A1 were genotyped in a total of 462 AAs from Washington, D.C. and Chicago area. Twenty GWAS identified VDPG variants were genotyped in a subset of subjects (n=332). West Africa Ancestry (WAA) was estimated using STRUCTRE from 105 ancestry informative markers typed. Then, we tested for association adjusting for WAA, age, and skin color. Results: Eight GWAS identified SNPs (five in GC, one in CYP2R1, and two in DHCR7/NADSYN1) were associated with serum 25(OH)D levels and/or vitamin D deficiency. Among darker-skinned AAs, the VDR SNP rs11568820 (Cdx2), was significantly associated (P Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4481. doi:1538-7445.AM2012-4481