Study: Genetic Variants in Skin Pigmentation Linked to Vitamin D Deficiency

Researchers in a City of Hope-led data study conducted a genome-wide association study using the data of 1076 African Americans to analyze the genetics of skin pigmentation in this group to test whether the identified genetic variants are linked to vitamin D deficiency in African Americans.

"We should not shy from this new study looking at the genetics of skin color and its effects on vitamin D deficiency because being 'colorblind' is what has led to the widespread health disparities that we as a society are now trying to address," said Rick Kittles, PhD, director of the Division of Health Equities at Beckman Research Institute of City of Hope, in a press release. "Skin color has strong social and biological significance—social because of race and racism and biological because over 70% of African Americans are vitamin D deficient, resulting in increased risk for cancer and cardiovascular disease.”

This was the first genome-wide association study of skin pigmentation in African Americans, according to the study authors. Study participants self-identified as African American, and blood samples for DNA analysis and vitamin D levels were collected at recruitment. Scientists then measured the sun-protected area of the skin in the inner upper arms of participants using a digital reflectometer.

Various factors, such as aging, outdoor activities, and consistent UV exposure over the years, may influence skin pigmentation and the association between skin pigmentation and vitamin D levels, according to the study. The researchers found that skin pigmentation gene variants, rather than skin pigmentation, measured using a reflectometer were associated with serum vitamin D levels.

Further, the scientists found 3 regions (SLC24A5, SLC45A2 and OCA2) in the genes of African Americans with strong links to skin color and severe vitamin D deficiency. The genetic variant rs2675345, which is near a region in the gene called SLC24A5, showed the strongest association with skin pigmentation and vitamin D deficiency.

Previous studies have shown that individuals with darker skin pigmentation require longer or more intense ultraviolet radiation exposure to synthesize sufficient levels of vitamin D. The current study’s authors said they hope the findings lead into future investigations that examine the newly identified risk score in physicians’ offices, potentially creating a precision medicine tool.

"This study is an example of the interplay of race and skin color on health and how if we ignore things such as the color of a person's skin, we may be ignoring potential medical issues, thus contributing to health care disparities," Kittles said in a press release. "Our study provides new knowledge about an easily modifiable factor such as vitamin D supplementation and inherited genetic factors affecting vitamin D deficiency in African Americans. With more research, in the future physicians could offer patients of color with an inexpensive way to reduce their risk of vitamin deficiency, which ultimately could help protect against certain cancers."

REFERENCE

Genetic variants for skin color in African Americans linked to vitamin D deficiency. ScienceDaily. Published February 18, 2021. Accessed March 19, 2021. https://www.sciencedaily.com/releases/2021/02/210218142820.htm