A 2009 study found that the Japanese in Central Japan and Chiba share a genetic trait with the Han Chinese Hakka and Minnam populations (with origins in Central China) – high frequencies of their ALDH2*504Lys allele marker and concluded that migrants likely carried the gene marker from ancient populations in East China to Japan During the Yayoi period. The marker is associated with high incidence rates of oesophageal cancer. See excerpts from the study below:
Figure 1. The geographic distribution of ALDH2*504Lys allele frequency. The grey scale refers to the interpolated allele frequency and correspondences are on the right, e.g. 0.12 means an allele frequency of 12% in the region. The open red triangles represent the locations of the population samples. The encircling black lines are the 0.12 and 0.24 frequency borders.
“In total, the map shows a pattern of a single center of expansion within East Asia. The highest frequencies appear in a restricted area in Southeast China, among the Han Chinese in south Fujian province and east Guangdong province (the Hakka and Minnam populations), decreasing gradually to the north and west. Hakka from Changting County in Fujian have the highest frequency, 40.9%. The Hakka population samples from Taiwan and Sichuan also exhibit high frequencies, indicating that Hakka have maintained a high frequency during their migrations. The allele frequencies in other Han Chinese populations range from 9% to 40%, exhibiting a cline clearly decreasing from southeast to northwest, except for two small peaks in Shanghai in East China and Shandong in Central China.
Another high frequency area for the ALDH2*504Lys allele is Central Japan with 34.1% in Chiba. However, this high frequency area seems to be an extension from East China. The frequency decreases from around 30% in Honshu to around 10% in Ryukyu and Hokkaido, corresponding well to the migration history of modern Japanese (the descendants of Yayoi People, Hammer et al., 2006). Therefore, it is most probable that the ALDH2*504Lys allele in Japan was brought by the early Yayoi migrants from mainland East Asia.”
The researchers also “hypothesize that the oriental ALDH2*504Lys variant might have originated in the ancient Han Chinese population in Central China and spread to most areas of East Asia with the expansion of Han Chinese and their genetic influences on neighboring populations over the past few thousand years.”
Source of study: Hui Li, et al., Refined Geographic Distribution of the Oriental ALDH2*504Lys (nee 487Lys) Variant, Annals of Human Genetics, Volume 73, Issue 3, pages 335–345, May 2009 doi: 10.1111/j.1469-1809.2009.00517.x
