This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cancer health disparities among African Americans are increasing. Vitamin D is suspected to play a role in several cancers and other chronic conditions with a higher incidence among African Americans. These studies are aimed at understanding if this disparity is due to prevalence of single nucleotide polymorphisms (SNPs) in vitamin D receptor (VDR) or VDR response elements (VDREs). Differences in serum vitamin D between African American and Caucasian participants will be associated with VDR genotype (short/short, short/long, long/long) and polymorphic variants occurring within VDRE located in VDR, CYP24A1 (24-hydroxylase), and CYP3A4. This study will be conducted with 154 healthy African American and 154 healthy Caucasian Penn State student participants during non-Summer months. (A pilot study was conducted previously, thus an additional 104 African American and 104 Caucasian participants are necessary.) Association between the serum vitamin D level and genotypes will be evaluated adjusting for age, sex, genetic ancestry, skin reflectance (melanin index), sunlight exposure and serum calcium levels will be determined. The SNPs will be determined in blood spots and lymphocyte DNA by re-sequencing of areas of the genes and comparing to the reference sequences. A DermaSpectrometer (CyberDerm, Media, Pa., USA) will be used three times on the upper inner side (medial aspect) of each arm with melanin index measurements averaged.