How many populations set foot through the Patagonian door? Genetic composition of the current population of Bahía Blanca (Argentina) based on data from 19 Alu polymorphisms

Interethnic admixture and the evolution of Latin American populations

A general introduction to the origins and history of Latin American populations is followed by a systematic review of the data from molecular autosomal assessments of the ethnic/continental (European, African, Amerindian) ancestries for 24 Latin American countries or territories. The data surveyed are of varying quality but provide a general picture of the present constitution of these populations. A brief discussion about the applications of these results (admixture mapping) is also provided. Latin American populations can be viewed as natural experiments for the investigation of unique anthropological and epidemiological issues.

European ancestry decreases the risk of early onset, severe lupus nephritis in a single center, multiethnic pediatric lupus inception cohort

Purpose: To determine whether pediatric SLE patients without European ancestry are at higher risk for development of severe lupus nephritis (ISN/RPS class III, IV or V). Methods: Ninety-eight of 101 patients with pediatric SLE (age <18 years at diagnosis) were enrolled. Race/ethnicity of four grandparents, socioeconomic status (SES) and language proficiency were collected. The primary outcome was time to development of severe lupus nephritis. Results: Based on patient report of four grandparent ancestry, 29% had at least one grandparent of European ancestry (14% had all four grandparents of European ancestry). Patients without European ancestry were 46% Hispanic, 47% Asian, and 3% African American. In the entire 98 patient cohort, 12% had ≥3 different ancestries. Patients without European ancestry had significantly lower SES levels and English proficiency. There was no significant difference between patients with or without European ancestry in duration of SLE, age of onset, and lag time between symptoms and diagnosis. Patients with at least one grandparent of European ancestry had a decreased risk of developing severe lupus nephritis, which remained significant after controlling for age, gender, SES and English proficiency (hazard ratio 0.4, 95% confidence interval 0.2–0.9). Conclusion: This study demonstrates that presence of at least one grandparent of European ancestry decreases the risk of severe lupus nephritis, a finding that is not explained by measurable socioeconomic differences and language barriers.

Autosomal and X chromosome Alu insertions in Bolivian Aymaras and Quechuas: two languages and one genetic pool

Thirty-two polymorphic Alu insertions (18 autosomal and 14 from the X chromosome) were studied in 192 individuals from two Amerindian populations of the Bolivian Altiplano (Aymara and Quechua speakers: the two main Andean linguistic groups), to provide relevant information about their genetic relationships and demographic processes. The main objective was to determine from genetic data whether the expansion of the Quechua language into Bolivia could be associated with demographic (Inca migration of Quechua-speakers from Peru into Bolivia) or cultural (language imposition by the Inca Empire) processes. Allele frequencies were used to assess the genetic relationships between these two linguistic groups. Our results indicated that the two Bolivian samples showed a high genetic similarity for both sets of markers and were clearly differentiated from the two Peruvian Quechua samples available in the literature. Additionally, our data were compared with the available literature to determine the genetic and linguistic structure, and East-West differentiation in South America. The close genetic relationship between the two Bolivian samples and their differentiation from the Quechua-speakers from Peru suggests that the Quechua language expansion in Bolivia took place without any important demographic contribution. Moreover, no clear geographical or linguistic structure was found for the Alu variation among South Amerindians.