Study Of Malaysian Tribe Could Help Find Asian Skin Color Genes

A genetic investigation of a Malaysian tribe may help to explain why East Asians have light skin but lower skin cancer rates than Europeans.

AsianScientist (Sep. 3, 2012) – A genetic investigation of a Malaysian tribe by a team of international researchers may help to explain why East Asians have light skin but lower skin cancer rates than Europeans.

Previous research using zebrafish by Penn State College of Medicine’s Dr. Keith Cheng identified the gene in Europeans that differs from West Africans and contributes to a lighter skin color. Mutations in the SLC24A5 and SLC45A2 genes are largely responsible for European pigmentation, showing only single amino acid differences between Europeans and West Africans.

But while East Asians of Chinese, Japanese, and Korean ethnicity are also light skinned, these European alleles are not present, suggesting that while both groups’ lighter skin color evolved to allow for better creation of vitamin D in northern climates, they did so in a different way.

This difference also affects skin cancer rates; Europeans have 10 to 20 times higher rates of melanoma than Africans, while lighter skinned East Asians have the same melanoma rates as Africans. The researchers wanted to identify the gene mutations that led to the difference in skin cancer rates for both groups.

“By finding the differences, we have the potential to find ways to make people with the European ancestry genes less susceptible to skin cancer,” said Cheng.

Finding the unidentified mutations may pose a problem, as researchers must study a population that includes a blend of original African ancestry and East Asian ancestry, with little European contribution.

The Senoi, one of three indigenous tribes from Peninsular Malaysia, meet this condition. The Senoi are believed to include ancestry of a dark-skinned tribe called the Negrito, and a regional Mongoloid population of Indo-China, such as the Proto-Malay. Since the skin color of the Senoi is darker than that of Northeast Asians, researchers will be able to focus on finding the primary genetic mutation of light skin color in Asians without seeing further skin lightening mutations.

Khai C. Ang, a postdoctoral fellow in the Cheng lab, visited the Senoi, developed a positive relationship with them, and was able to collect 371 blood samples. Ang’s research that characterized the Senoi’s skin color was published recently in the journal PLoS ONE.

“As the world is becoming globalized, populations are becoming increasingly mixed,” Ang said. “Time is running out and it will become increasingly difficult to establish how East Asian skin colors evolved.”

The researchers will now map genes in the DNA using the collected samples to identify which might be responsible for the skin color of East Asians. Candidate genes and mutations will then be tested in zebrafish for verification.

The article can be found at: Ang KC et al. (2012) Skin Color Variation in Orang Asli Tribes of Peninsular Malaysia.

——

Source: PSU; Photo: jason highway tan/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Aparna received a PhD in Translational Medicine (Immunology) on a scholarship from the University of Milano-Bicocca, Italy. She is now a research scientist at the Agency for Science, Technology and Research (A*STAR), Singapore.

Related Stories from Asian Scientist