Analyses of frequency profiles of markers on disease or drug-response related genes in diverse populations are important for the dissection of common diseases. We report the results of analyses of data on 405 SNPs from 75 such genes and a 5.2 Mb chromosome, 22 genomic region in 1871 individuals from diverse 55 endogamous Indian populations. These include 32 large (>10 million individuals) and 23 isolated populations, representing a large fraction of the people of India. We observe high levels of genetic divergence between groups of populations that cluster largely on the basis of ethnicity and language. Indian populations not only overlap with the diversity of HapMap populations, but also contain population groups that are genetically distinct. These data and results are useful for addressing stratification and study design issues in complex traits especially for heterogeneous populations.

Parkinson's disease (PD), a neurodegenerative disease, affects approximately 1% of the elderly population over 60 years. Prevalence of PD varies between 18 and 148 per 1,00,000 population world-wide 1 . Age-adjustment and restriction to studies using similar methodology reduce the variation between 102 and 190 per 1,00,000 population in Western countries. The Euro-Parkinson study 2 reported the prevalence rates from five European countries namely USA, Germany, France, UK and Sweden within a similar range. As the world population ages, it is estimated that the cost of PD will continue to rise. Since its description by James Parkinson in 1817, many attempts have ABSTRACT: Background: While the cause of Parkinson's disease (PD) remains unknown, evidence suggests certain environmental factors, such as well water drinking, herbicides, pesticides exposure and neurotoxins, may trigger the chain of oxidative reactions culminating in the death of dopaminergic neurons in substantia nigra to cause Parkinsonism. To investigate the possible impact of environmental risk factors for idiopathic PD, a case-control study was performed in the Eastern India. Methods: During the period from January 1st, 2006 and December 10th, 2009, 175 PD patients (140 men, 35 women) and 350 non-Parkinson age-sex matched controls were included in the study. Subjects were given a structured neurological examination and completed an administered questionnaire which elicited detailed information on demographic data, pesticides, herbicides family history, occupation, dietary and smoking habits. Results: The multivariate analysis revealed that family history of PD, pesticide exposure, exposure to toxins other than pesticides and herbicides, rural living and previous history of depression were associated with increased risk of PD, whereas, smoking appeared to be a protective factor. Well water drinking for at least five years, though a significant risk factor on univariate analysis (OR=4.5, 95% CI=2.1-9.9), could not be proved significant in multivariate analysis. Head trauma, vegetarian dietary habit, occupation involving physical exertion and exposure to domestic pets were not as significant risk factors. Conclusion: Results of our study support the hypothesis of multifactorial etiology of PD with environmental factors acting on a genetically susceptible host. Les sujets ont subi un examen neurologique structuré et ont rempli un questionnaire sur les données démographiques, l'exposition à des pesticides et à des herbicides, l'histoire familiale, le métier ou la profession, les habitudes alimentaires et le tabagisme. Résultats : L'analyse multivariée a montré que l'histoire familiale de MP, l'exposition à des pesticides, l'exposition à des toxines autres que des pesticides et des herbicides, la vie à la campagne et l'histoire antérieure de dépression étaient associées à un risque accru de MP. Le tabagisme semblait être un facteur de protection. Bien que la consommation d'eau de puits pendant au moins 5 ans ait été un facteur de risque significatif à l'a...

The population genetics of the Indian subcontinent is central to understanding early human prehistory due to its strategic location on the proposed corridor of human movement from Africa to Australia during the late Pleistocene. Previous genetic research using mtDNA has emphasized the relative isolation of the late Pleistocene colonizers, and the physically isolated Andaman Island populations of Island South-East Asia remain the source of claims supporting an early split between the populations that formed the patchy settlement pattern along the coast of the Indian Ocean. Using whole-genome sequencing, combined with multiplexed SNP typing, this study investigates the deep structure of mtDNA haplogroups M31 and M32 in India and the Andaman Islands. The identification of a so far unnoticed rare polymorphism shared between these two lineages suggests that they are actually sister groups within a single haplogroup, M31'32. The enhanced resolution of M31 allows for the inference of a more recent colonization of the Andaman Islands than previously suggested, but cannot reject the very early peopling scenario. We further demonstrate a widespread overlap of mtDNA and cultural markers between the two major language groups of the Andaman archipelago. Given the "completeness" of the genealogy based on whole genome sequences, and the multiple scenarios for the peopling of the Andaman Islands sustained by this inferred genealogy, our study hints that further mtDNA based phylogeographic studies are unlikely to unequivocally support any one of these possibilities.

Background: An early dispersal of biologically and behaviorally modern humans from their African origins to Australia, by at least 45 thousand years via southern Asia has been suggested by studies based on morphology, archaeology and genetics. However, mtDNA lineages sampled so far from south Asia, eastern Asia and Australasia show non-overlapping distributions of haplogroups within pan Eurasian M and N macrohaplogroups. Likewise, support from the archaeology is still ambiguous.

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