Origin and genetic differentiation of three Native Mexican groups (Purépechas, Triquis and Mayas): contribution of CODIS-STRs to the history of human populations of Mesoamerica.

BACKGROUND: CODIS-STRs in Native Mexican groups have rarely been analysed for human identification and anthropological purposes. AIM: To analyse the genetic relationships and population structure among three Native Mexican groups from Mesoamerica. SUBJECTS AND METHODS: 531 unrelated Native individuals from Mexico were PCR-typed for 15 and 9 autosomal STRs (Identifiler™ and Profiler™ kits, respectively), including five population samples: Purépechas (Mountain, Valley and Lake), Triquis and Yucatec Mayas. Previously published STR data were included in the analyses. RESULTS: Allele frequencies and statistical parameters of forensic importance were estimated by population. The majority of Native groups were not differentiated pairwise, excepting Triquis and Purépechas, which was attributable to their relative geographic and cultural isolation. Although Mayas, Triquis and Purépechas-Mountain presented the highest number of private alleles, suggesting recurrent gene flow, the elevated differentiation of Triquis indicates a different origin of this gene flow. Interestingly, Huastecos and Mayas were not differentiated, which is in agreement with the archaeological hypothesis that Huastecos represent an ancestral Maya group. Interpopulation variability was greater in Natives than in Mestizos, both significant. CONCLUSION: Although results suggest that European admixture has increased the similarity between Native Mexican groups, the differentiation and inconsistent clustering by language or geography stresses the importance of serial founder effect and/or genetic drift in showing their present genetic relationships.

Population data for 15 loci (Identifiler Kit) in a sample from the Valley of Mexico.

We analyzed 242 individuals from the Valley of Mexico, including the larger and more cosmopolitan city of this country. They were PCR-typed for 15 STR loci with the AmpFlSTR Identifiler PCR Amplification Kit (Applied Biosystems). Allele frequencies for each STR were estimated and compared to previous reports. Genotype distribution by locus and by two-loci combination was in agreement with Hardy-Weinberg expectations for all fifteen STRs. This STR system in Mexican-mestizos presented a combined probability of exclusion (PE) and discrimination (PD) longer than 99.999%, respectively.

Population data of nine STRs of Mexican-Mestizos from Mexico City.

One hundred and thirteen individuals were PCR-typed for nine STR loci with the AmpFlSTR Profiler Plus PCR amplification kit, including the following autosomal STRs: D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317 and D7S820. Allele frequencies for each STR were estimated, and they were compared to other populations. Genotype distribution by locus and by two-loci combination was in agreement with Hardy-Weinberg expectations for all nine STRs. For this region of Mexico, the combined probability of exclusion (PE) and power of discrimination (PD) were estimated: PE=99.964% and PD>99.999%.

Haplotype frequencies of the PowerPlex Y system in a Mexican-Mestizo population sample from Mexico City.

The PowerPlex Y system including 11 Y-STRs (DYS19, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS385, DYS437, DYS438 and DYS439) was analyzed by capillary electrophoresis in 357 males from Mexico City. Haplotype frequency for this system was reported. The haplotype diversity was 99.56+/-0.04%, and gene diversity ranged from 51.4% for DYS393 to 92.5% for DYS385. AMOVA tests including previous reports from Mexico (Chihuahua and Jalisco States), demonstrated significant genetic heterogeneity between north and western populations regarding Mexico City, justifying the establishment of local databases in this country for male-identification purposes.