6 research outputs found

    Haplotype diversity and linkage disequilibrium at the DRD2 locus among the tribes of western and southern regions of India

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    Background: Dopamine receptor D2 (DRD2) is an important gene having functional significance in the fields of neuropsychiatry and pharmacology and also has importance in evolutionary studies. Materials and Methods: This study was undertaken to find out the haplotype distribution and linkage disequilibrium (LD) pattern for the three TaqI sites (TaqI \u2032A\u2032, TaqI \u2032B\u2032 and TaqI \u2032D\u2032) in the DRD2 gene in 232 unrelated individuals from five ethno-linguistically distinct endogamous tribal populations; Siddis and Gonds of Uttara Kannada district, Karnataka; Varli and Kolgha of Valsad district, Gujarat; and Dangi Konkana of Dang district, Gujarat. The genotype data obtained after molecular analysis of the three DRD2 sites was subjected to statistical analysis such as calculation of allele frequencies, haplotype frequencies among others. Subsequently, a neighbor-joining tree was also constructed from the data obtained. Results: The three DRD2 sites were found to be polymorphic in all the populations. All the populations showed high levels of heterozygosities. Out of the eight possible haplotypes, most populations shared seven haplotypes. Of all the populations, Siddis showed the highest frequency of the ancestral haplotype B2D2A1 (11.4%). Significant LD was found to exist for TaqI \u2032A\u2032 and TaqI \u2032B\u2032 sites in both the populations. Conclusion: The findings are in concurrence with those from other Indian studies, especially from Dravidian-speaking South Indian populations. Similar pattern of diversity observed for ethnically and linguistically diverse populations in the present study is indicative of complex structure of Indian populations

    Genetic Affinities of the Siddis of South India: An Emigrant Population of East Africa

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    Historical records indicate that the Portuguese brought the African moved into the interior regions of the state of Karnataka, India, and have remained there ever since. Over time the Siddis have experienced considerable cultural changes because of their proximity to neighboring population groups. To understand the biological consequences of these changes, we studied the Siddis to determine the extent of genetic variation and the contributions from the African, European, and Indian ancestral populations. In the present study we typed the Siddis for 20 polymorphic serological, red cell, and Alu insertion-deletion loci. The overall pattern of phenotype (and genotype) distribution is in accordance with Hardy-Weinberg expectations. Considering the ethnohistorical records and the availability of secondary-source genetic data, we used two data sets in the analysis: one comprising eight serological and red cell enzyme markers with eight population groups and another comprising six Alu insertion-deletion markers with seven tribal groups of South India. The dendrograms generated from these two data sets on the basis of genetic distance analysis between the selected populations of African, European, and Indian descent reveals that the Siddis are closer to the Africans than they are to the South Indian populations. Genetic admixture analysis using a dihybri model (19 loci) and a trihybrid model (10 loci and 8 loci) shows that the predominant influence comes from the Africans, a lesser contribution from the South Indians, and a slight contribution from the Portuguese. Thus the original composition of the African genes among the Siddis has been diluted to some extent by the contribution from southern Indian population groups. There is no nonrandom association of alleles among a set of 10 genetic marker system considered in the present study. The demonstration of genetic homogeneity of the Siddis, despite their admixed origin, suggests the utility of this population for genetic and epidemiological studies

    Haplotype diversity and linkage disequilibrium at the DRD2 locus among the tribes of western and southern regions of India

    No full text
    Background: Dopamine receptor D2 (DRD2) is an important gene having functional significance in the fields of neuropsychiatry and pharmacology and also has importance in evolutionary studies. Materials and Methods: This study was undertaken to find out the haplotype distribution and linkage disequilibrium (LD) pattern for the three TaqI sites (TaqI ′A′, TaqI ′B′ and TaqI ′D′) in the DRD2 gene in 232 unrelated individuals from five ethno-linguistically distinct endogamous tribal populations; Siddis and Gonds of Uttara Kannada district, Karnataka; Varli and Kolgha of Valsad district, Gujarat; and Dangi Konkana of Dang district, Gujarat. The genotype data obtained after molecular analysis of the three DRD2 sites was subjected to statistical analysis such as calculation of allele frequencies, haplotype frequencies among others. Subsequently, a neighbor-joining tree was also constructed from the data obtained. Results: The three DRD2 sites were found to be polymorphic in all the populations. All the populations showed high levels of heterozygosities. Out of the eight possible haplotypes, most populations shared seven haplotypes. Of all the populations, Siddis showed the highest frequency of the ancestral haplotype B2D2A1 (11.4%). Significant LD was found to exist for TaqI ′A′ and TaqI ′B′ sites in both the populations. Conclusion: The findings are in concurrence with those from other Indian studies, especially from Dravidian-speaking South Indian populations. Similar pattern of diversity observed for ethnically and linguistically diverse populations in the present study is indicative of complex structure of Indian populations
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