José Edgardo Dipierri

Beringian Standstill and Spread of Native American Founders

Native Americans derive from a small number of Asian founders who likely arrived to the Americas via Beringia. However, additional details about the intial colonization of the Americas remain unclear. To investigate the pioneering phase in the Americas we analyzed a total of 623 complete mtDNAs from the Americas and Asia, including 20 new complete mtDNAs from the Americas and seven from Asia. This sequence data was used to direct high-resolution genotyping from 20 American and 26 Asian populations. Here we describe more genetic diversity within the founder population than was previously reported. The newly resolved phylogenetic structure suggests that ancestors of Native Americans paused when they reached Beringia, during which time New World founder lineages differentiated from their Asian sister-clades. This pause in movement was followed by a swift migration southward that distributed the founder types all the way to South America. The data also suggest more recent bi-directional gene flow between Siberia and the North American Arctic.

Geographic patterns of genome admixture in Latin American Mestizos.

The large and diverse population of Latin America is potentially a powerful resource for elucidating the genetic basis of complex traits through admixture mapping. However, no genome-wide characterization of admixture across Latin America has yet been attempted. Here, we report an analysis of admixture in thirteen Mestizo populations (i.e. in regions of mainly European and Native settlement) from seven countries in Latin America based on data for 678 autosomal and 29 X-chromosome microsatellites. We found extensive variation in Native American and European ancestry (and generally low levels of African ancestry) among populations and individuals, and evidence that admixture across Latin America has often involved predominantly European men and both Native and African women. An admixture analysis allowing for Native American population subdivision revealed a differentiation of the Native American ancestry amongst Mestizos. This observation is consistent with the genetic structure of pre-Columbian populations and with admixture having involved Natives from the area where the Mestizo examined are located. Our findings agree with available information on the demographic history of Latin America and have a number of implications for the design of association studies in population from the region.

Brief communication: Restricted geographic distribution for Y-Q* paragroup in South America.

We analyzed 21 paragroup Q* Y chromosomes from South American aboriginal and urban populations. Our aims were to evaluate the phylogenetic status, geographic distribution, and genetic diversity in these groups of chromosomes and compare the degree of genetic variation in relation to Q1a3a haplotypes. All Q* chromosomes from our series and five samples from North American Q* presented the derivate state for M346, that is present upstream to M3, and determined Q1a3* paragroup. We found a restrictive geographic distribution and low frequency of Q1a3* in South America. We assumed that this low frequency could be reflecting extreme drift effects. However, several estimates of gene diversity do not support the existence of a severe bottleneck. The mean haplotype diversity expected was similar to that for South American Q1a3* and Q1a3a (0.478 and 0.501, respectively). The analysis of previous reports from other research groups and this study shows the highest frequencies of Q* for the West Corner and the Grand Chaco regions of South America. At present, there is no information on whether the phylogenetic status of Q* paragoup described in previous reports is similar to that of Q1a3* paragroup though our results support this possibility.

Isonymy Structure of Buenos Aires City

Abstract The isonymy structure of Buenos Aires was studied based on its surname frequency. Information on 2,552,359 voters of the 28 Buenos Aires districts was used to estimate Laskers coefficient of relationship by isonymy (Ri), surname diversity according to Fishers a, the coefficient of consanguinity resulting from random isonymy (F), and Neis, Laskers and the Euclidean isonymy distances. These distances were correlated with geographic distances, which were calculated by assigning an arbitrary point to each district and measuring distances on a map of the city. The Ri × 105 and F × 104 averages of the districts located south of Rivadavia Avenue were higher (Ri = 66.08; F = 3.4) than those situated north of that avenue (Ri = 46.60; F = 2.4) (p < 0.001). Fishers a showed the opposite behavior (north, &agr; = 1,055.5; south, &agr; = 757.2). There was a significant correlation (p < 0.001) between geographic distance and Neis and the Euclidean distances (0.496 and 0.503, respectively), but the correlation was not significant for Laskers distance (0.051). These results indicate isolation by distance in the city of Buenos Aires and reveal subdivision of the metropolitan population, with greater consanguinity and a lesser variety of surnames in the districts located in the southern section of the city. This structure agrees with the fragmentation and social, cultural, and economic differences observed among the districts of this Latin American metropolis.

Mortalidad infantil por malformaciones congénitas en Argentina: análisis del quinquenio 2002-2006

OBJECTIVE To analyze the trend and spatial distribution of infant mortality from congenital malformations in Argentina between 2002 and 2006. MATERIALS AND METHODS Data were provided by the Ministry of Public Health. Congenital malformations were classified according to the International Classification of Diseases, 10th revision. Early neonatal, late neonatal and postneonatal infant mortality components, congenital malformations subgroups and specific malformations were estimated by departments, provinces, and regions to determine: a) Congenital malformations- related death rate; b) infant mortality rate due to congenital malformations. Both indicators were correlated with the respective departmental latitude/longitude. RESULTS Infant mortality rate due to congenital malformations was 3.33 per thousand and congenital malformations- related death rate 22.7%. Both indicators showed great spatial variability and did not correlate to latitude/longitude. The lowest infant mortality rate due to congenital malformations and congenital malformations-related death rates were found in Patagonia and the Argentine northeast, respectively. The early neonatal period showed the highest infant mortality rate due to congenital malformations and congenital malformations-related death rates was over 20% in the 3 periods. The Argentine northwest and Argentine northeast showed the lower congenital malformations rates-related death rates in the three components than Centro, Cuyo and Patagonia. CONCLUSIONS The pattern of infant mortality from congenital malformations in Argentina is similar to that of developed countries, characterized by a decrease of infant mortality rate due to congenital malformations and increase of congenital malformations-related death rates, with a prevailing contribution of heart and nervous system malformations.

Surnames in Bolivia: A study of the population of Bolivia through isonymy

In Bolivia, the Hispanic dual surname system is used. To describe the isonymic structure of Bolivia, the surname distribution of 12,139,448 persons registered in the 2006 census data was studied in 9 districts and 112 provinces of the nation, for a total of 23,244,064 surnames. The number of different surnames found was 174,922. Matrices of isonymic distances between the administrative units (districts and provinces) were constructed and tested for correlation with geographic distance. In the 112 provinces, isonymic distances were correlated with geographic distance (r = 0.545 ± 0.011 for Euclidean, 0.501 ± 0.012 for Neis, and 0.556 ± 0.010 for Laskers distance). The multiple regression of the surname effective number (α), equivalent to the allele effective number in a genetic system, was nonsignificant on latitude and longitude; however, it was highly significant and negative on altitude (r = -0.72). Because the Andes extend from north to south in west-central Bolivia, random inbreeding was lowest in the eastern districts, and highest in mountainous western Bolivia. Average α for the provinces was 122 ± 2; for the districts, it was 216 ± 29, and for the whole of Bolivia it was 213. The geographical distribution of α in the provinces is compatible with the settlement of subsequent groups of migrants moving from east and north toward the center and south of Bolivia. The relative frequency of indigenous surnames is correlated positively with altitude. This suggests that the country was populated by recent low-density demic diffusion over a low-density indigenous population. This may have been a common phenomenon in the immigration to tropical South America.

Genetic structure and admixture in urban populations of the Argentine North-West

Background: From the ethnic point of view, the Argentine North-West (ANW) constitutes one of the most noticeable areas in the country due to the cultural peculiarities that integrate it to the Andean world and the ethno-historical and demographic characteristics of how it became populated. Aim: The study analysed the genetic structure and diversity of the ANW urban populations, and the contribution of parental populations to its genetic pool. Subjects and methods: Previously reported data on allele frequencies of HLA-A and HLA-B loci of 1293 individuals from Jujuy, Salta, Tucumán, Santiago del Estero, Catamarca and La Rioja were used. Our estimates include: (a) genetic intra-population diversity; (b) genetic distances between populations; (c) linkage disequilibrium (LD); (d) admixture rates and genetic distances with respect to three parental populations (European, American Indian and African). Results: Low intra-population genetic differentiation and low genetic distances between populations were found. Differential LD distribution varied according to province, with 60% variance due to intra-population differences. The Spanish contribution (50%) predominated in ANW, followed by the American Indian (40%) and African (10%) contributions, and a marked inter-population heterogeneity of genetic admixture rates was observed. The shortest genetic distance was found in the American Indian parental population, and the longest in the African parental population. Conclusion: Five hundred years after the Spanish conquest, urban populations at ANW that have probably been subject to the same evolutionary forces present low genetic diversity and a similar genetic structure. Genetic distances and admixture percentages observed agree with census and ethno-historical data on settlement in the region. Résumé. Arrière plan: Du point de vue ethnique, le Nord-Ouest de l’Argentine(NOA) constitue l’une des régions les plus remarquables du pays, par ses particularités culturelles qui l’intègrent au monde andin et par les circonstances ethno-historiques et démographiques de son peuplement. But: Cette étude analyse la structure génétique et la diversité des populations urbaines du NOA ainsi que la contribution de populations mères à son patrimoine génétique. Sujets et méthodes:. On a utilisé les données déjà publiées des fréquences alléliques des loci HLA-A et HLA-B de 1293 individus de Jujuy, Salta, Tucuman, Santiago del Estero, Catarmarca et La Rioja. Nos estimations incluent : (a) la diversité génétique intra-populationnelle ; (b) les distances génétiques entre populations ; (c) le déséquilibre de linkage (DL) ; (d) les taux de métissage et les distances par rapport à trois populations mères (européenne, amérindienne et africaine). Résultats: On a trouvé une faible différenciation génétique intra-populationnelle ainsi que de faibles distances génétiques entre populations. La distribution du DL varie suivant les provinces, 60% de la variance étant dus à des différences intra-populationnelle. La contribution espagnole (50%) est prédominante dans le NOA, suivie par la composante amérindienne (40%) et africaine (10%). On a observé une forte hétérogénéité interpopulationnelle des taux de métissage. La distance génétique la plus courte a été trouvée dans la population mère amérindienne et la plus longue dans la population mère africaine. Conclusion: Cinq cent ans après la conquête espagnole, les populations urbaines du NOA qui ont probablement été soumises aux mêmes forces évolutives, présentent une diversité génétique basse et une structure génétique similaire. Les distances génétiques et les pourcentages de métissage observés s’accordent avec les recensements et les données ethno-historiques sur la colonisation de la région. Zusammenfassung. Hintergrund: Unter ethnischen Gesichtspunkten ist der Argentinische Nordwesten (ANW) eine der bemerkenswertesten Gegenden des Landes, und zwar aufgrund der kulturellen Besonderheiten, die ihn in die Welt der Anden integrieren, und aufgrund seiner ethnisch-historischen und demographischen Merkmale unter dem Aspekt, wie die Besiedlung stattfand. Ziel: Die Studie analysierte die genetische Struktur und Diversität von städtischen Populationen aus dem Argentinischen Nordwesten und den Beitrag väterlicher Populationen zum genetischen Pool. Probanden und Methoden: Es wurden früher publizierte Daten betreffend die Allelfrequenzen von HLA-A und HLA-B loci von 1293 Personen aus Jujuy, Salta, Tucumán, Santiago del Estero, Catamarca und La Rioja benutzt. Unsere Schätzungen umfassten: (a) die genetische Diversität innerhalb der Populationen; (b) den genetischen Abstand zwischen den Populationen; (c) das Kopplungsungleichgewicht (linkage disequilibrium, LD); (d) die Zumischungsraten und den genetischen Abstand unter Berücksichtigung dreier elterlicher Populationen (Europäer, Amerikanische Indianer and Afrikaner). Ergebnisse: Es wurden eine geringe genetische Differenzierung innerhalb der Populationen und geringe genetische Abstände zwischen den Populationen gefunden. Die unterschiedliche Verteilung des Kopplungsungleichgewichts variierte je nach Provinz, mit 60% Varianz aufgrund von Unterschieden innerhalb der Populationen. Der Spanische Einfluss (50%) herrschte in ANW vor, gefolgt von Amerikanisch-Indianischen (40%) und Afrikanischen (10%) Einflüssen, und es wurde eine bedeutsame Heterogenität der genetischen Zumischungsrate zwischen den Populationen beobachtet. Der geringste genetische Abstand befand sich in der Amerikanisch-Indianischen Elternpopulation, der weiteste in der Afrikanischen Elternpopulation. Zusammenfassung: Fünfhundert Jahre nach der Spanischen Eroberung zeigen städtische Populationen in ANW, die vermutlich denselben evolutionären Kräften ausgesetzt waren, eine niedrige genetische Diversität und eine ähnliche genetische Struktur. Die beobachteten genetischen Abstände und prozentuale Zumischung stimmen mit Zensus- und ethnisch-historischen Daten zur Besiedlung dieses Gebietes überein. Resumen. Antecedentes: Desde el punto de vista étnico, la Argentina del Noroeste (ANW) constituye una de las áreas más notables del país debido a las peculiaridades culturales que la integran en el mundo Andino y a las características etno-históricas y demográficas de su poblamiento. Objetivos: El estudio analizó la estructura genética y la diversidad de las poblaciones de la ANW y la contribución de las poblaciones parentales a su pool génico. Sujetos y Métodos: Se utilizaron datos previamente reportados sobre frecuencias alélicas de los loci HLA-A y HLA-B, de 1293 individuos de Jujuy, Salta, Tucumán, Santiago del Estero, Catamarca y La Rioja. Nuestras estimaciones incluyen: a) la diversidad genética intrapoblacional, b) las distancias genética entre poblaciones, c) el desequilibrio de ligamiento (DL), d) las tasas de mezcla y las distancias genéticas respecto a tres poblaciones parentales (europea, amerindia y africana). Resultados: Se encontró una baja diferenciación genética intrapoblacional y reducidas distancias genéticas entre poblaciones. La distribución del DL diferencial variaba según la provincia, con una varianza del 60% debida a las diferencias intrapoblacionales. En la ANW predominó la contribución española (50%), seguida de las contribuciones amerindia (40%) y africana (10%) y se observó una marcada heterogeneidad interpoblacional en las tasas de mezcla genética. La menor distancia genética se encontró en la población parental amerindia y la mayor en la población parental africana. Conclusión: Quinientos años después de la conquista española, las poblaciones urbanas de la ANW, que han estado probablemente sometidas a las mismas fuerzas evolutivas, presentan una baja diversidad genética y una estructura genética similar. Las distancias genéticas y los porcentajes de mezcla observados concuerdan con los datos del censo y los etno-históricos existentes sobre el poblamiento de la región.

A Study of the Population of Paraguay through Isonymy

In order to describe the isonymic structure of Paraguay, the distribution of 4,843,868 surnames of 2,882,163 persons was studied in the 18 departments and 237 districts of the nation. The correlations between isonymic and geographic distances for departments were r = 0.713 ± 0.052 for Euclidean distance, 0.597 ± 0.074 for Neis and 0.582 ± 0.076 for Laskers, and for districts r = 0.320 ± 0.007, 0.235 ± 0.009 and 0.422 ± 0.008, respectively. Average α was 151 for the entire country, 140.6 ± 6.5 for departments and 108.2 ± 2.7 for districts. The geographical distribution of districts’α is compatible with the settlement of subsequent groups of migrants moving from South towards the Centre and North of Paraguay. The geographical analysis of the first three components of Laskers isonymy distance matrix is in agreement with such a process. The prevalence of Spanish–Amerindian ethnic groups and the relative absence of indigenous surnames (absence due mainly to the forced surname change of 1848) is in agreement with the diffusion of Spanish speaking males over a low‐density area populated by indigenous groups. The present distribution of Y‐markers and mt‐markers in the available studies in most Latin American populations is compatible with this process.

Microevolutionary processes due to landscape features in the province of Jujuy (Argentina)

Objectives: We seek to evaluate the influence of a diverse and rugged physical environment on the genetic background of human populations.

Tendencia secular del peso de nacimiento en Argentina (1992-2002): un estudio poblacional

INTRODUCTION Birth weight (BW) is considered an important measure of the health status of a population. Objectives. 1) to assess secular trends in average BW, low birth weight (LBW,<2.500 g), very low birth weight (VLBW, < 1.500 g) and BW > or = 3.000 g of liveborn infants in Argentina; 2) calculate risks of LBW, VLBW and > or = 3.000 g; 3) influence of underreported birth weight. MATERIAL AND METHODS In this national-based study 7.113.931 liveborn infants born in Argentina from 1992 to 2002 were included. BW was assessed from the National Ministry of Public Health. Annuals mean BW and residual distribution (RD) following the Wilcox-Russell approach were calculated, and also LBW, VLBW and > or =3.000 g proportions. RESULTS A decrease of 32 g in average BW (p= 0.577) and 24 g between 2000 and 2002 (p <0.001) was observed. RD reached 4%. The significant increase in LBW (12%, p= 0.034) and VLBW (26%, p= 0.002) proportions was paralleled by a reduction of 3.6% in BW > or =3.000 g (p= 0.011, average 75.2%). Risks of being LBW and VLBW were 1.13 (95% CI 1.12-1.15) and 1.30 (1.25-1.35), respectively; for BW > or =3.000 g was 0.86 (95% CI 0.85-0.87). No significant correlations between underreported BW and proportions of LBW (r= 0.10) or VLBW (r= 0.01) were observed. CONCLUSION A negative secular trends of BW was observed, all categories of LBW and VLBW were increased, BW > 3.000 g was diminished and under-reported BW did not influenced these results.