Identifying signatures of natural selection in Indian populations.

In this study, we present the results of a genome-wide scan for signatures of positive selection using data from four tribal groups (Kokana, Warli, Bhil, and Pawara) and two caste groups (Deshastha Brahmin and Kunbi Maratha) from West of the Maharashtra State In India, as well as two samples of South Asian ancestry from the 1KG project (Gujarati Indian from Houston, Texas and Indian Telugu from UK). We used an outlier approach based on different statistics, including PBS, xpEHH, iHS, CLR, Tajima's D, as well as two recently developed methods: Graph-aware Retrieval of Selective Sweeps (GRoSS) and Ascertained Sequentially Markovian Coalescent (ASMC). In order to minimize the risk of false positives, we selected regions that are outliers in all the samples included in the study using more than one method.

MC1R diversity and its role in skin pigmentation variation in West Maharashtra, India.

Objectives: MC1R polymorphisms have been reported to be under a selective constraint in populations inhabiting high UVR regions such as Africans; however, these patterns are not consistent. Here we analyze the MC1R gene in West Maharashtra, India to see if sequence diversity corresponds to their diverse pigmentary profiles and if MC1R is constrained in dark skinned tribal as compared to lighter skinned caste populations.

Methods: A 2648 bp region of this gene was sequenced in 102 individuals and the data was compared for π, ϴ diversity indices.

Novel insights on demographic history of tribal and caste groups from West Maharashtra (India) using genome-wide data.

The South Asian subcontinent is characterized by a complex history of human migrations and population interactions. In this study, we used genome-wide data to provide novel insights on the demographic history and population relationships of six Indo-European populations from the Indian State of West Maharashtra. The samples correspond to two castes (Deshastha Brahmins and Kunbi Marathas) and four tribal groups (Kokana, Warli, Bhil and Pawara).

A Genome-Wide Association Study of Skin and Iris Pigmentation among Individuals of South Asian Ancestry.

South Asia has a complex history of migrations and is characterized by substantial pigmentary and genetic diversity. For this reason, it is an ideal region to study the genetic architecture of normal pigmentation variation. Here, we present a meta-analysis of two genome-wide association studies (GWASs) of skin pigmentation using skin reflectance (M-index) as a quantitative phenotype.

Identifying signatures of positive selection in pigmentation genes in two South Asian populations.

Objectives: Skin pigmentation is a polygenic trait showing wide phenotypic variations among global populations. While numerous pigmentation genes have been identified to be under positive selection among European and East populations, genes contributing to phenotypic variation in skin pigmentation within and among South Asian populations are still poorly understood. The present study uses data from the Phase 3 of the 1000 genomes project focusing on two South Asian populations-GIH (Gujarati Indian from Houston, Texas) and ITU (Indian Telugu from UK), so as to decode the genetic architecture involved in adaptation to ultraviolet radiation in South Asian populations.

Association of genetic variants with skin pigmentation phenotype among populations of west Maharashtra, India.

Objectives: South Asians exhibit extensive variation in skin melanin index (MI) which is observed across the broader region of South Asia as well as within restricted geographic regions. However, the genetic variants associated with variation in the skin pigmentation phenotype are poorly understood in these populations. The present study examines the association between MI measures and genetic variants from 5 candidate pigmentation genes among 533 individuals representing 6 populations of West Maharashtra.

Skin pigmentation variation among populations of West Maharashtra, India.

Objectives: Global patterns of skin pigmentation have evolved as an adaptation to local ultraviolet radiation (UVR). Indian populations exposed to intense UVR show great variation in skin pigmentation. The UVR-based selection model cannot satisfactorily address the high prevalence of light skin among these populations.