An update and frequency distribution of Y chromosome haplogroups in modern Japanese males.

Japanese males belong to the Y chromosome C1a1, C2, D1a2a, D1a2a-12f2b, O1b2, O1b2a1a1, O2a2b1, and O2a1b haplogroups. Notably, the regional frequency of each haplogroup is homogeneous. Owing to recent developments in genome sequencing technology, the phylogenetic tree of Y chromosome haplogroups is updated annually. Therefore, in this study, we aimed to provide an update on the Y chromosome haplogroups of modern Japanese males and examine their regional distributions. Using 1,640 samples of Japanese males from seven Japanese cities (Nagasaki, Fukuoka, Tokushima, Osaka, Kanazawa, Kawasaki, and Sapporo), haplogroups C1a1, C2, D1a2a, D1a2a-12f2b, O1b2, and O1b2a1a1 were updated based on the latest phylogenetic tree. Haplogroup C1a1 was mainly classified into C1a1a1a and C1a1a1b subgroups; C1a1a1b was more common in Tokushima and Osaka than in the other regions. Haplogroup C2 was mainly classified into C2a, C2b1a1a, C2b1a1b, C2b1a2, and C2b1b subgroups and exhibited frequency differences in Osaka. Haplogroup D1a2a was classified into D1a2a1c1 and D1a2a2 subgroups, and its frequency varied between Tokushima and Osaka. Haplogroup D1a2a-12f2b was classified into D1a2a1a2b1a1a and D1a2a1a3 subgroups; however, no significant frequency differences were observed. Haplogroup O1b2 was classified into O1b2a1a2a1a, O1b2a1a2a1b, and O1b2a1a3 subgroups, with frequency differences between Nagasaki and Kanazawa. Haplogroup O1b2a1a1 was mainly classified into O1b2a1a1a, O1b2a1a1b, and O1b2a1a1c subgroups; however, no significant frequency differences were observed. Our findings suggest that gene flow in the Kinki region is caused by human migration.