Emma Alfaro

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.

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.

The LMS method and weight and height centiles in Jujuy (Argentina) children.

Human growth and its resulting patterns display a great inter- and intra-population heterogeneity that reflects the quality of life, health and nutritional condition of populations. The aim of this work was to expand the knowledge about the growth of Jujenean children by statistical procedures that graphically express the relation of anthropometric variables to age and allow their comparison with specific references. Anthropometric data came from 9092 children (0-5 years) from various localities of Jujuy province (northwest Argentina) located at 1200 m above sea level (ma.s.l.). The centiles of weight for age (W/A) and height for age (H/A) were obtained by the LMS method using maximum penalized likelihood. A statistical and graphic comparison was made with the corresponding Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) centile references. In general, estimated centiles were lower than those in both references. Discrepancies for H/A in comparison with the CDC reference ranged between 1.09+/-0.59% and 1.66+/-0.34%, and for W/A between 1.82+/-1.56% and 3.36+/-1.4%. In comparison with the WHO reference, discrepancies ranged from 1.38+/-0.65% to 1.87+/-0.41% for H/A, and from 1.12+/-1.28% to 2.74+/-1.49% for W/A. Centile discrepancies were attributed to the characteristics of early childhood feeding and the interaction of a set of biological and mesological factors that the Jujenean population is exposed to. Growth and nutritional conditions of this population should be evaluated with the WHO reference, for it reflects the recent growth pattern of biologically and culturally healthy children raised in favourable conditions, a pattern that also reflects that of Jujenean children.

Mortalidad infantil por anencefalia en la Argentina: Análisis espacial y temporal (1998-2007)

OBJECTIVE Analyze the spatial and temporal distribution of infant mortality by anencephaly in Argentina in relation with folic acid fortification phases. POPULATION AND METHODS Data came from certificates of live births and deaths in children under 1 year, for the 1998-2007 period (Argentine Ministry of Health). The infant mortality rate attributable to anencephaly for Argentina, geographical regions, provinces and departments were estimated according to the different phases of mandatory fortification with folic acid. Secular trend of infant mortality rate attributable to anencephaly and death risk due to anencephaly, spatial distribution by infant mortality rate attributable to anencephaly cluster and its correlation to latitude and longitude were also analyzed. RESULTS Reduced risk of mortality due to anencephaly (53%) was observed at national level. The greatest decline occurred in Cuyo (69%) and lowest in the Northeast (35%) at regional level. Considerable infant mortality rate attributable to anencephaly heterogeneity was found at departmental level and less at provincial level. A cluster of 5.15/10 000 infant mortality rate attributable to anencephaly was identified in the northeast of Buenos Aires province, consisting of 29 departments, significantly different from the rest of the country. CONCLUSIONS While there was a statistically significant negative secular trend of infant mortality rate attributable to anencephaly, spatial disparities persist. The geographical distribution of anencephaly would guide the search for environmental/ genetic risk factors and strengthen primary prevention strategies, through mandatory fortification, folate intake and folic acid supplementation.

Geographic altitude, surnames, and height variation of Jujuy (Argentina) conscripts

The height records of 48,589 conscripts born in Jujuy between 1870 and 1960 were examined in order to study the variation in adult male height (AMH) in terms of geographical altitude and surnames. Data were clustered by origin of surnames (divided into native and foreign names), decades, and according to the four Jujenean geographical regions distributed along an altitudinal gradient (Puna, Quebrada, Valle, and Ramal). The variation of surnames, geographical altitude, and time on human height were examined by analysis of variance. Regardless of the drafting year, individuals in the four regions bearing foreign surnames proved significantly taller (P < 0.001) than those who had a native surname. Average height, regardless of ethnic group, presented a reverse relationship to geographical altitude. A higher AMH was found in individuals bearing foreign surnames in Jujuy and lower ones in the population located in the highlands and bearing native surnames. Interregional and intergroup AMH variations would be affected by the complex interaction between geographical altitude and factors associated to it and by the ethnic characteristics of these population as well.

Random inbreeding, isonymy, and population isolates in Argentina

Population isolates are an important tool in identifying and mapping genes of Mendelian diseases and complex traits. The geographical identification of isolates represents a priority from a genetic and health care standpoint. The purpose of this study is to analyze the spatial distribution of consanguinity by random isonymy (FST) in Argentina and its relationship with the isolates previously identified in the country. FST was estimated from the surname distribution of 22.6 million electors registered for the year 2001 in the 24 provinces, 5 geographical regions, and 510 departments of the country. Statistically significant spatial clustering of FST was determined using the SaTScan V5.1 software. FST exhibited a marked regional and departamental variation, showing the highest values towards the North and West of Argentina. The clusters of high consanguinity by random isonymy followed the same distribution. Recognized Argentinean genetic isolates are mainly localized at the north of the country, in clusters of high inbreeding. Given the availability of listings of surnames in high-capacity storage devices for different countries, estimating FST from them can provide information on inbreeding for all levels of administrative subdivisions, to be used as a demographic variable for the identification of isolates within the country for public health purposes.