Genetic lineage of the Amami islanders inferred from classical genetic markers

The genetic structure of the people of mainland Japan and Okinawa has been gradually unveiled in recent years. However, previous anthropological studies dealing with people in the Amami islands, located between mainland Japan and Okinawa, were less informative because of the lack of genetic data. In this study, we collected DNAs from 104 subjects in two of the Amami islands, Amami-Oshima island and Kikai island. We analyzed the D-loop region of mtDNA, four Y-STRs, and four autosomal nonsynonymous SNPs to clarify the Amami islanders genetic structure compared with peoples in Okinawa, mainland Japan, and other regions of East Asia. We found that the Amami islanders showed a genetically intermediate position between mainland Japan and Okinawa in mtDNA and Y-STR. However, the frequencies of several autosomal SNPs in the Amami islanders indicated a significant difference from mainland Japanese, which may be because of the gene flow from Okinawa but not natural selection. Moreover, extremely high or low frequencies of several alleles implied a founder effect in Kikai islanders. Note that there is room for the interpretation of the results because of the small sample size and number of alleles in the present study. Geographically broad and detailed samplings and genome-wide analyses are awaited.