Distribution of local ancestry and evidence of adaptation in admixed populations

• Published in: Scientific reports Vol. 9; no. 1; pp. 13900 - 12
• Main Authors: Secolin, Rodrigo, Mas-Sandoval, Alex, Arauna, Lara R., Torres, Fábio R., de Araujo, Tânia K., Santos, Marilza L., Rocha, Cristiane S., Carvalho, Benilton S., Cendes, Fernando, Lopes-Cendes, Iscia, Comas, David
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.09.2019; Nature Publishing Group; Nature Research
• Subjects: 45; 45/61; 631/208; 631/208/182; Adaptation, Physiological - genetics; Black or African American; Black People - genetics; Brazil; Chromosome 8; Chromosome rearrangements; Chromosomes - genetics; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2 - genetics; Evolutionary biology; Female; Genetics; Genetics, Population - methods; Genome, Human - genetics; Genomes; Haplotypes; Haplotypes - genetics; Humanities and Social Sciences; Humans; Male; multidisciplinary; Positive selection; Precision medicine; Protein Phosphatase 1 - genetics; Science; Science (multidisciplinary); United States; White People - genetics; Brazil; United States
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-50362-2

Admixed American populations have different global proportions of European, Sub-Saharan African, and Native-American ancestry. However, individuals who display the same global ancestry could exhibit remarkable differences in the distribution of local ancestry blocks. We studied for the first time the distribution of local ancestry across the genome of 264 Brazilian admixed individuals, ascertained within the scope of the Brazilian Initiative on Precision Medicine. We found a decreased proportion of European ancestry together with an excess of Native-American ancestry on chromosome 8p23.1 and showed that this is due to haplotypes created by chromosomal inversion events. Furthermore, Brazilian non-inverted haplotypes were more similar to Native-American haplotypes than to European haplotypes, in contrast to what was found in other American admixed populations. We also identified signals of recent positive selection on chromosome 8p23.1, and one gene within this locus, PPP1R3B , is related to glycogenesis and has been associated with an increased risk of type 2 diabetes and obesity. These findings point to a selection event after admixture, which is still not entirely understood in recent admixture events.