• RANAJIT DAS

      Articles written in Journal of Genetics

    • Investigating the West Eurasian ancestry of Pakistani Hazaras

      RANAJIT DAS PRIYANKA UPADHYAI

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      The Hazaras are a distinct ethnic group from central Afghanistan and northwestern Pakistan of Mongoloid descent. Here, we sought to dissect the genetic admixture history of the Pakistani Hazaras and investigated their likely affiliation to ancient and extant West Eurasian populations. Our results indicated that the likely proportion of West Eurasian ancestry was low in the Hazaras and could be attributed putatively to a combination of Steppe populations from Early/Middle Bronze Age or Middle/Late Bronze Age and the Neolithic Iranians. Our results expand upon the current understanding and provide an improved resolution into the population history of the Pakistani Hazaras.

    • Developing ancestry informative marker panel for Nigeria- Cameroonian chimpanzees

      S. ANJANA SAI PRADIVYA SAMMETA RANAJIT DAS

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      Chimpanzees (Pan troglodytes), with a dwindling population size, are distributed across sub-Saharan Africa. They are classified into two biogeographical clusters comprising of four subspecies: a western African cluster that includes P. t. verus and P. t. ellioti and a central/eastern African cluster that includes P. t. troglodytes and P. t. schweinfurthii. While the genetic distinctness of Nigeria-Cameroonian chimpanzees (P. t. ellioti) from western chimpanzees has been known for a while, the fine structures within P. t. ellioti population has remained under-studied. In this study, we developed the first ever ancestry informative marker (AIMs) panel that can detect the fine population structure within Nigeria-Cameroonian chimpanzees with high resolution. We compared four commonly used AIMs determining strategies, namely Infocalc algorithm, Wright’s FST, smart principal component analysis (SmartPCA) and ADMIXTURE to first identify the best approach and then developed an AIMs panel of 435 SNPs employing the consensus of the four approaches (n = 129),with additional supplements from the best two approaches (Infocalc and ADMIXTURE). To the best of our knowledge, we have developed the first-ever AIMs panel for chimpanzees, which can greatly aid in their planned reintroduction to the natural habitat, maintaining their genetic integrity through planned captive breeding, and in tracking illegal trading across the globe.

    • Population genetic variation of SLC6A4 gene, associated with neurophysiological development

      SHYAMALA H. HANDE SWATHY M. KRISHNA KOMALROOP KAUR SAHOTE NIROSHA DEV TING PEI ERL KOVINDRAAM RAMAKRISHNA RENUKA RAVIDHRAN RANAJIT DAS

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      The serotonin transporter 5-HTT is encoded by a single gene SLC6A4. Polymorphisms in SLC6A4 has been associated with awide variety of neurological and psychiatric disorders including increased risk of posttraumatic stress disorder, higher likelihood fordepression, obsessive–compulsive disorder (OCD), increased hostility and criminal behaviour. Genes associated with complex diseasesoften exhibit strong signatures of purifying selection compared to others. Further, discernible population specific variation in the signatureof natural selection have been observed for several complex disease-related genes. In this project we aimed to investigate the populationgenetic variation of the serotonin transporter gene (SLC6A4), focussing on the single nucleotide polymorphisms (SNPs). To this end, weemployed 2504 individuals around the globe available in 1000 Genome project Phase III data and classified them into five ethnic groups:Americans (AMR), Europeans (EUR), Africans (AFR), East Asians (EAS) and South Asians (SAS). Principal component analysis (PCA)performed on all annotated SNPs of SLC6A4 depicted clear clustering between Africans and the rest of the world along PC1, and EastAsians and other non-African populations along PC2. Further, these SNPs were found to be under strong selection pressure especiallyamong East Asian populations with significantly high positive cross-population extended haplotype homozygosity scores compared toAfricans, indicating that SLC6A4 has likely undergone a strong selective sweep among the East Asians in the recent past. Our study canpotentially explain the association between polymorphisms in SLC6A4, and major depression and suicidal tendencies among people of EastAsian ancestry and the absence of such associations among people of European ancestry.

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