Admixture dynamics in Hispanics: A shift in the nuclear genetic ancestry of a South American population isolate

Abstract

Although it is well established that Hispanics generally have a mixed Native American, African, and European ancestry, the dynamics of admixture at the foundation of Hispanic populations is heterogeneous and poorly documented. Genetic analyses are potentially very informative for probing the early demographic history of these populations. Here we evaluate the genetic structure and admixture dynamics of a province in northwest Colombia (Antioquia), which prior analyses indicate was founded mostly by Spanish men and native women. We examined surname, Y chromosome, and mtDNA diversity in a geographically structured sample of the region and obtained admixture estimates with highly informative autosomal and X chromosome markers. We found evidence of reduced surname diversity and support for the introduction of several common surnames by single founders, consistent with the isolation of Antioquia after the colonial period. Y chromosome and mtDNA data indicate little population substructure among founder Antioquian municipalities. Interestingly, despite a nearly complete Native American mtDNA background, Antioquia has a markedly predominant European ancestry at the autosomal and X chromosome level, which suggests that, after foundation, continuing admixture with Spanish men (but not with native women) increased the European nuclear ancestry of Antioquia. This scenario is consistent with historical information and with results from population genetics theory.genetic history ͉ migration ͉ latinos ͉ Founder effect ͉ cultural selection

Association of copy number variation in the FCGR3B gene with risk of autoimmune diseases

“…36,37 Previous work from our group has shown the homogeneity of our cohorts and control group. 38,39 Exclusion criteria consisted of hematological disorders, active infection or breastfeeding.…”

Asociación de variantes en genes de las proteínas desacoplantes con diabetes mellitus tipo 2 en una población del nordeste colombiano

“…A todos los participantes se les hizo una entrevista genealógica, previamente utilizada, que registra el lugar de nacimiento de los antecesores hasta los bisabuelos con el fin de establecer su procedencia (19,24).…”

“…Se ha demostrado que la prevalencia de diabetes mellitus tipo 2 está muy correlacionada con la ascendencia amerindia (15), que en poblaciones hispánicas de Estados Unidos las personas con ascendencia africana tiene mayor prevalencia de diabetes mellitus tipo 2 que las que poseen ascendencia europea (16) y que el riesgo para diabetes es significativamente menor en individuos con alta porcentaje de mezcla genética europea en comparación con la mezcla amerindia (15,17). Los datos obtenidos a partir de marcadores clásicos (grupos sanguíneos y proteínas) sugieren que el componente genético de esta población es principalmente europeo (70%), con una menor contribución amerindia y africana (15% cada una) (18), y los porcentajes de los linajes del cromosoma Y (94% europeo, 5% africano y 1% amerindio) y del ADN mitocondrial (90% amerindio, 8% africano y 2% europeo) muestran un sesgo en el patrón de cruces en la población fundadora (19).…”

The Genetic Diversity of the Americas

“…Initial analyses used mtDNA and Y chromosome data, which allow a direct assessment of paternal and maternal ancestry. A dramatic early example of this approach was provided by the population of Antioquia in Colombia, where ~90% of Y chromosome lineages are of European origin, whereas ~90% of mtDNA lineages are Native American, indicating that the foundation of the population from this province overwhelmingly involved European men and native women, although this is not specifically recorded in historical documents (12,25,26). Similar analyses of other Ibero-American populations have often documented paternal lineages as mainly European, whereas maternal lineages are predominantly Native American or African (3,7,28,41,55,60,88).…”