Population structure and admixture in Cerro Largo, Uruguay, based on blood markers and mitochondrial DNA polymorphisms.

Recent studies of the Uruguayan population revealed different amounts of Amerindian and African genetic contributions. Our previous analysis of Afro-Uruguayans from the capital city of the Department of Cerro Largo showed a high proportion of African genes, and the effects of directional mating involving Amerindian women. In this paper, we extended the analysis to a sample of more than 100 individuals representing a random sample of the population of the whole Department. Based on 18 autosomal markers and one X-linked marker, we estimated 82% European, 8% Amerindian, and 10% African contributions to their ancestry, while from seven mitochondrial DNA site-specific polymorphic markers and sequences of hypervariable segment I, we determined 49% European, 30% Amerindian, and 21% African maternal contributions. Directional matings between Amerindian women and European men were detected, but differences involving Africans were not significant. Data about the specific origins of maternal lineages were also provided, and placed in a historical context.

Risk factors for hepatitis B and C in multi-transfused patients in Uruguay.

BACKGROUND: In spite of the progress made in the prevention of transfusion-transmitted infections over the last years, these still occur. It was considered that infection by hepatitis B (HBV) and C (HCV) viruses could be a major problem in Uruguay, especially among high-risk individuals, such as multi-transfused patients. OBJECTIVES: To assess the prevalence of HBV and HCV infection among multi-transfused Uruguayan patients and the impact of serological screening; to evaluate the role of number of transfusions and other potential risk factors for the acquisition of HBV and HCV infection. STUDY DESIGN: Cross-sectional study of HCV antibodies, HBV surface antigen (HBsAg) and HBV core antibodies (HBcAc) in 409 multi-transfused patients. RESULTS: Of 409 patients studied, 147 (35.9%) received blood products due to acute bleeding, 118 (28.9%) were hemato-oncological, 75 (18.3%) hemophiliacs, 64 (15.6%) were on hemodialysis and 5 (1.2%) suffered sickle cell anemia. Prevalence of HCV antibody was 12.7%. Of the HCV positive patients, 45 were hemophiliacs, for a prevalence rate of 60.0%. The prevalence rates for hemodialysis and acute bleeding patients were 6.3% and 2.0%, respectively. Prevalence of HBsAg was 1.0%; 16.6% of subjects were positive for HBcAc. The prevalence rates of HBcAc were 48.0%, 15.0% and 3.1% among hemophiliacs, acute bleeding and hemodialysis patients, respectively. There was a direct relationship between the number of products transfused and prevalence of both hepatitis C antibodies and HBcAc. Higher prevalence of HCV and HBcAc was observed among the group of patients who received transfusions before the systematic screening of blood donors. CONCLUSIONS: Exposure to blood transfusions was the main risk factor for HCV and HBV infection. The systematic serological screening of blood donors was highly effective in reducing transfusion transmitted infections.

Unequal contributions of male and female gene pools from parental populations in the African descendants of the city of Melo, Uruguay.

In admixed populations, genetic contributions from males and females of specific parental populations can be of different proportions due to past directional mating during the process of genetic admixture. In this research paper, we provide evidence of such male- and female-specific differential admixture components of African, European, and American Indian origin in an admixed population from the city of Melo, in the northeastern region of Uruguay. From data on 11 autosomal markers from a sample of 41 individuals of mixed African descent, we estimated 47% African, 38% European, and 15% Amerindian contributions. In contrast, 6 mtDNA site-specific polymorphic markers showed that the mtDNA genome of these individuals was 52% African, 19% European, and 29% Amerindian, while from 3 Y-specific polymorphic sites, we estimated 30% African, 64% European, and 6% Amerindian contributions. We argue that this heterogeneity of admixture estimates results from disproportionate unions of European males with African and American Indian females from which this mixed African population was formed. Also, we argue that the asymmetry of the admixture estimates from the three sets of markers (autosomal, mtDNA, and Y-linked) is a result of the changes in the direction of mating during the history of the population. Implications of such evidence of directional mating are discussed, indicating the need of further demographic data for a quantitative assessment of the impact of directional mating on genetic structure of admixed populations.