mtDNA Haplogroup X: An Ancient Link Between Europe/Western Asia and North America?

Am J Hum Genet. 1998 Dec;63(6):1852-61. doi: 10.1086/302155.

Abstract

On the basis of comprehensive RFLP analysis, it has been inferred that approximately 97% of Native American mtDNAs belong to one of four major founding mtDNA lineages, designated haplogroups "A"-"D." It has been proposed that a fifth mtDNA haplogroup (haplogroup X) represents a minor founding lineage in Native Americans. Unlike haplogroups A-D, haplogroup X is also found at low frequencies in modern European populations. To investigate the origins, diversity, and continental relationships of this haplogroup, we performed mtDNA high-resolution RFLP and complete control region (CR) sequence analysis on 22 putative Native American haplogroup X and 14 putative European haplogroup X mtDNAs. The results identified a consensus haplogroup X motif that characterizes our European and Native American samples. Among Native Americans, haplogroup X appears to be essentially restricted to northern Amerindian groups, including the Ojibwa, the Nuu-Chah-Nulth, the Sioux, and the Yakima, although we also observed this haplogroup in the Na-Dene-speaking Navajo. Median network analysis indicated that European and Native American haplogroup X mtDNAs, although distinct, nevertheless are distantly related to each other. Time estimates for the arrival of X in North America are 12,000-36,000 years ago, depending on the number of assumed founders, thus supporting the conclusion that the peoples harboring haplogroup X were among the original founders of Native American populations. To date, haplogroup X has not been unambiguously identified in Asia, raising the possibility that some Native American founders were of Caucasian ancestry.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Asia, Western / ethnology
  • Asian Continental Ancestry Group / genetics*
  • Base Sequence
  • Consensus Sequence
  • DNA, Mitochondrial / genetics*
  • Europe / ethnology
  • European Continental Ancestry Group / classification
  • European Continental Ancestry Group / genetics*
  • Gene Frequency
  • Haplotypes / genetics*
  • Humans
  • Indians, North American / classification
  • Indians, North American / genetics*
  • Locus Control Region / genetics
  • North America
  • Phylogeny
  • Polymorphism, Restriction Fragment Length
  • Sequence Analysis, DNA

Substances

  • DNA, Mitochondrial