Characterization of mtDNA Haplogroups in 14 Mexican Indigenous Populations

Abstract

In this descriptive study we investigated the genetic structure of 513 Mexican indigenous subjects grouped in 14 populations (Mixteca-Alta, Mixteca-Baja, Otomi, Purépecha, Tzeltal, Tarahumara, Huichol, Nahua-Atocpan, Nahua-Xochimilco, Nahua-Zitlala, Nahua-Chilacachapa, Nahua-Ixhuatlancillo, Nahua-Necoxtla, and Nahua-Coyolillo) based on mtDNA haplogroups. These communities are geographically and culturally isolated; parents and grandparents were born in the community. Our data show that 98.6% of the mtDNA was distributed in haplogroups A1, A2, B1, B2, C1, C2, D1, and D2. Haplotype X6 was present in the Tarahumara (1/53) and Huichol (3/15), and haplotype L was present in the Nahua-Coyolillo (3/38). The first two principal components accounted for 95.9% of the total variation in the sample. The mtDNA haplogroup frequencies in the Purépecha and Zitlala were intermediate to cluster 1 (Otomi, Nahua-Ixhuatlancillo, Nahua-Xochimilco, Mixteca-Baja, and Tzeltal) and cluster 2 (Nahua-Necoxtla, Nahua-Atocpan, and Nahua-Chilacachapa). The Huichol, Tarahumara, Mixteca-Alta, and Nahua-Coyolillo were separated from the rest of the populations. According to these findings, the distribution of mtDNA haplogroups found in Mexican indigenous groups is similar to other Amerindian haplogroups, except for the African haplogroup found in one population.

A great diversity of Amerindian mitochondrial DNA ancestry is present in the Mexican mestizo population

“…The lower frequency of C haplotypes in the central region agrees with the low frequency of this haplogroup in indigenous populations from the valley of Mexico. 13 In contrast, half of the eight individuals from the north region had this haplotype, which agrees with the high frequency of this haplogroup in indigenous populations from the north, such as the Huichol (41%) and Tarahumara (38%) populations. 13,15,16 The frequency of haplogroup D1 was similarly low in all geographical regions analyzed.…”

“…This agrees with the higher frequency of B haplotypes in some indigenous populations from the central regions, such as Nahuatl (27-40%), or from the south, such as Mixe (33.3%). 13,15,16 The data also suggest that the higher frequency of Amerindian ancestry in the central region is accounted essentially by the increased frequency of B haplotypes. The frequency of the transversion A16182C in B2 haplotypes was more frequent in the central region (55.5%, 15 out of 27 individuals) than in Mexico City (41.6%, 5 out 12 individuals) B2 haplotypes, but this difference was not significant.…”

“…There is a higher proportion of individuals with Caucasoid ancestry in Mexico City (35-71%) and the northern regions (35-55%) than in the central regions (21%) around Mexico City and the southern regions (4.2-43%) of Mexico, whereas the African ancestry predominates in the coastal regions (22-41%). 12 On the other hand, European ancestry, explored using mitochondrial DNA (mtDNA), was absent in the indigenous population [13][14][15][16] and was very low in the mestizos either from the north (5.3%) 17 or from Mexico City (3.2%). 12,18 Although those Mexican mestizos come from modern populations, the fact that mtDNA is maternally inherited 19 without recombination indicates that the mestizo mitochondrial genome has initially been inherited from indigenous women.…”

“…15,24,25 Those Amerindian haplogroups were recently termed A2, C1, B2 and D1, once there were more available data of the complete mtDNA genome sequence. [26][27][28] As most studies that analyzed mtDNA polymorphism in the Mexican population used mainly restriction fragment length polymorphisms (RFLPs), 13,17,18,29 and there are no available data from full control region sequences, the knowledge of mtDNA diversity is limited and it has not been extensively analyzed.…”

Evaluating the Farming/Language Dispersal Hypothesis with genetic variation exhibited by populations in the Southwest and Mesoamerica

“…As found in Results and Discussion, this population movement played little role in our understanding of the relationships between populations of the Southwest and Mesoamerica. In contrast to non-Athapaskan Southwest populations, Mesoamerican populations exhibit high frequencies of haplogroup A with moderate to low frequencies of haplogroup B (6,7,(34)(35)(36)(37). These haplogroup patterns crosscut linguistic and geographic boundaries within both regions, and predate European contact in the Southwest (38,39) and Central Mexico (40,41).…”