PMC:3492649 / 28856-31344 JSONTXT

{"project":"2_test","denotations":[{"id":"23166524-21737057-44844091","span":{"begin":734,"end":736},"obj":"21737057"},{"id":"23166524-21741027-44844092","span":{"begin":1938,"end":1940},"obj":"21741027"}],"text":"Population Admixture in South Asia\nAll the published results in this area so far have been focused on populations in India. There were recently 2 studies on the Siddis, which are a group of people showing evident genetic admixture in India. The Siddis (Afro-Indians) are a tribal population whose members live in coastal Karnataka, Gujarat, and some parts of Andhra Pradesh. Historical records indicate that the Portuguese brought the Siddis to India from Africa about 300-500 years ago; members of this population are believed to be descendants of the Bantu-speaking population of Africa. However, there is little information about their more precise ancestral origins. One Indian group, led by Dr. Mukerji, studied this population [98] based on genomewide SNP data generated using Affymetrix 50K chips. The authors carried out this study by using a set of 18,534 autosomal markers common between Indian, CEPH-HGDP, and HapMap populations. Principal components analysis clearly revealed that the African-Indian population derived its ancestry from Bantu-speaking west African as well as Indo-European-speaking north and northwest Indian population(s). STRUCTURE and ADMIXTURE analyses show that overall, the OG-W-IPs derived 58.7% of their genomic ancestry from their African past and have very little inter-individual ancestry variation (8.4%). The extent of LD also reveals that the admixture event has been recent. Functional annotation of genes encompassing the AIMs that are closer in allele frequency to the Indian ancestral population revealed significant enrichment of biological processes, such as ion channel activity, and cadherins. They briefly examined the implications of determining the genetic diversity of this population, which could provide opportunities for studies involving admixture mapping.\nThe second group, led by Dr. Thangaraj, performed a genomewide survey to understand the population history of the Siddis [99]. Using hundreds of thousands of autosomal markers, they showed that the Siddis inherited ancestry from Africans, Indians, and possibly Europeans (Portuguese). Additionally, analyses of the uniparental (Y-chromosomal and mitochondrial DNA) markers indicate that the Siddis trace their ancestry to Bantu speakers from sub-Saharan Africa. They estimated that the admixture between the African ancestors of the Siddis and neighboring South Asian groups probably occurred in the past 8 generations (-200 years ago), consistent with historical records."}