Phylogeny of Y-chromosome haplogroup C3b-F1756, an important paternal lineage in Altaic-speaking populations.

In previous studies, a specific paternal lineage with a null value for the Y-chromosome short tandem repeat (Y-STR) marker DYS448 was identified as common among Mongolic- and Turkic-speaking populations. This paternal lineage (temporarily named C3*-DYS448del) was determined to be M217+, M93-, P39-, M48-, M407-, and P53.1-, and its origin and phylogeny remain ambiguous. Here, we analyzed Y-chromosome sequences of 10 male that are related this paternal lineage and redefined it as C3b1a1a1a-F1756 (C3b-F1756). We generated a highly revised phylogenetic tree of haplogroup C3b-F1756, including 21 sub-clades and 360 non-private Y-chromosome polymorphisms. Additionally, we performed a comprehensive analysis of the C3*-DYS448del lineage in eastern Eurasia, including 18 270 samples from 297 populations. Whole Y-chromosome sequences, Y-STR haplotypes, and frequency data were used to generate a distribution map, a network, and age estimations for lineage C3*-DYS448del and its sub-lineages. Considering the historical records of the studied populations, we propose that two major sub-branches of C3b-F1756 may correspond to early expansions of ancestors of modern Mongolic- and Turkic-speaking populations. The large number of newly defined Y-chromosome polymorphisms and the revised phylogenetic tree for C3b-F1756 will assist in investigation of the early history of Altaic-speaking populations in the future.