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Research report

Research report

The researchers are dedicating themselves every day to research activities for customer satisfaction.
We asked them about their research outcomes.

Report file Vol.2
Relationship between pigmentation spots and the origins of the Japanese people

Q.How did you get started with this research?

 

It is well known that ultraviolet radiation and aging are the main causes of pigmentation spots. However, it is also true that some people are more prone than others to pigmentation spots. I hypothesized that our inborn characteristics, namely our genes, might play an important role in determining who would be affected, and I started to investigate the genes responsible for pigmentation spots.

 

Q.What are pigmentation genes?

Our research focused on MC1R, which is a key gene in the production of melanin, the cause of pigmentation spots (Fig. 1). Our hypothesis was that there are individual variations in this gene, and that it might somehow affect the likelihood of developing pigmentation spots.
We investigated the MC1R gene in 244 Japanese individuals and found that there are two types of the MC1R gene. One makes it comparatively difficult (normal-type) and one makes it easier (pigmentation-type) to develop pigmentation spots.
Among the 244 subjects, 60.7% were normal-type, 6.6% were pigmentation-type, and 32.8% were mixed-type with characteristics of both types of the MC1R gene.

Q.What is the relationship between pigmentation genes and the origins of the Japanese people?

We surveyed the distribution of the MC1R gene across Japan and found something interesting: pigmentation-type genes are more common in individuals originating from peripheral regions of Japan, specifically, Hokkaido, Tohoku, and Kyushu (Fig. 2).
We know that a comparatively large proportion of the genes from the Jomon era (ca. 131-3 BCE) are preserved in these regions. Based on the hypothesis that pigmentation-type genes derived from the Jomon people, we analyzed DNA samples provided by the National Museum of Science and Nature to investigate the presence of the MC1R gene in the Jomon people.
We found that 100% of the MC1R genes in the Jomon people were pigmentation-type, suggesting that the presence of these genes in modern-day individuals derives from the Jomon era (Fig. 3). In other words, it seems that the Jomon people were also prone to pigmentation spots!
The normal-type genes that make it comparatively difficult to develop pigmentation spots originate from the Yayoi people who came to Japan from continental Asia toward the end of Jomon era.

Q.What does this mean for modern-day Japanese people?

Today, Japanese people possess genes passed down from both the Jomon and Yayoi people; however, different people have different proportions of genes from each of the Jomon and Yayoi people. We scored modern-day individuals for features that are characteristic of the Jomon people (Jomon score), and investigated their relationship with pigmentation spots. We found that people with a high Jomon score, with characteristics such as double eyelids, well-defined features, and curly hair (Fig. 4), were at greater risk of developing pigmentation spots.
Conversely, people with the shallow features and single eyelids that are characteristic of the Yayoi people tended to be less likely to develop pigmentation spots.

Q.Talk about your future plans for genetic research.

 

By continuing to survey genes to further investigate the relationship between pigmentation spots and the origins of the Japanese people, I hope to develop new counseling and skin analysis techniques.

 
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