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BMC GenetBMC Genetics1471-2156BioMed Central London 1471-2156-5-231531765710.1186/1471-2156-5-23Research ArticleGenetic structure of four socio-culturally diversified caste populations of southwest India and their affinity with related Indian and global groups Rajkumar Revathi 1revathi_77@rediffmail.comKashyap VK 1vkk2k@hotmail.com1 DNA Typing Unit, Central Forensic Science Laboratory, 30 Gorachand Road, Kolkata, India-7000142004 19 8 2004 5 23 23 17 1 2004 19 8 2004 Copyright © 2004 Rajkumar and Kashyap; licensee BioMed Central Ltd.2004Rajkumar and Kashyap; licensee BioMed Central Ltd.This is an open-access article distributed under the terms of the Creative Commons Attribution License (), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background
A large number of microsatellites have been extensively used to comprehend the genetic diversity of different global groups. This paper entails polymorphism at 15 STR in four predominant and endogamous populations representing Karnataka, located on the southwest coast of India. The populations residing in this region are believed to have received gene flow from south Indian populations and world migrants, hence, we carried out a detailed study on populations inhabiting this region to understand their genetic structure, diversity related to geography and linguistic affiliation and relatedness to other Indian and global migrant populations.

Results
Various statistical analyses were performed on the microsatellite data to accomplish the objectives of the paper. The heretozygosity was moderately high and similar across the loci, with low average GST value. Iyengar and Lyngayat were placed above the regression line in the R-matrix analysis as opposed to the Gowda and Muslim. AMOVA indicated that majority of variation was confined to individuals within a population, with geographic grouping demonstrating lesser genetic differentiation as compared to linguistic clustering. DA distances show the genetic affinity among the southern populations, with Iyengar, Lyngayat and Vanniyar displaying some affinity with northern Brahmins and global migrant groups from East Asia and Europe.

Conclusion
The microsatellite study divulges a common ancestry for the four diverse populations of Karnataka, with the overall genetic differentiation among them being largely confined to intra-population variation. The practice of consanguineous marriages might have attributed to the relatively lower gene flow displayed by Gowda and Muslim as compared to Iyengar and Lyngayat. The various statistical analyses strongly suggest that the studied populations could not be differentiated on the basis of caste or spatial location, although, linguistic affinity was reflected among the southern populations, distinguishing them from the northern groups. Our study also indicates a heterogeneous origin for Lyngayat and Iyengar owing to their genetic proximity with southern populations and northern Brahmins. The high-ranking communities, in particular, Iyengar, Lyngayat, Vanniyar and northern Brahmins might have experienced genetic admixture from East Asian and European ethnic groups.
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Background
The Indian subcontinent is regarded as a natural genetic laboratory, owing to the co-existence and interaction of socio-culturally, linguistically, ethnically and genetically diversified endogamous populations in a geographical terrain. It is believed that the earliest humans leaving Africa for Eurasia might have taken a coastal route across Saudi Arabia, through Iraq, Iran, to Pakistan and finally entered India along the coastlines [1]. A second wave of migration (~10,000 years ago) brought in Proto-Dravidian Neolithic farmers from Afghanistan, who were later displaced southwards by a large influx of Indo-European speakers ~3500 years ago in to the subcontinent [2,3]. The origin and settlement of the Indian people still remains intriguing, fascinating scientists to explore the impact of these past and modern migrations on the genetic diversity and structure of contemporary populations [4-6].

Anthropologically, southern and northern populations are distinct and these differences are further substantiated by (i) the presence of Neolithic sites in this region suggests that Neolithic people of southern India came from north by land and the west-coast by sea [7], (ii) the southern megaliths resemble closely with those of the Mediterranean and western-Europe, while those from northern India are similar to megaliths found in Iran and Baluchisthan [8], and (iii) the predominance of Dravidian language in this region as opposed to their secluded occurrence in central Asia and other parts of India, suggests that the Dravidian languages might have originated within India [9]. It is, thus, of considerable genetic interest to understand the genetic structuring and relationships of southern populations.

The present study was carried out on one of the largest southern states, Karnataka, positioned on the southwest coast of India, with a dwelling of about 50 million people. This expanse has been a rich source of prehistoric discoveries dating back to the Paleolithic era that are akin to those seen in Europe [7]. Karnataka has received continuous gene flow from different caste and linguistic groups residing in the adjoining areas of Maharashtra, Andhra Pradesh and Tamil Nadu [10], resulting in the congregation of a large number of diverse endogamous groups within this region. Its large coastline of about 400 Km also attracted the Portugese, Dutch and French traders, who were seeking more profitable ventures on the southern coast at large [2]. Southwest India is, thus, one of the most disparate terrains, with extensive colonization in the past and justifies an in-depth genetic study.

A few studies utilizing classical markers have been carried out on southern populations [5,11,12], including few communities of Karnataka [13,14]. However, sound inferences relating to their genetic structuring and diversity could not be drawn due to low discriminatory power of these markers. Recently, microsatellite markers have gained immense popularity in precisely defining population structure, diversity, affinities, gene flow and other crucial aspects associated with population genetics [15-21] because of the relative expediency, with which a large number of loci and alleles can be typed, facilitating the accumulation of vast data sets that can be readily analyzed with an extensive array of statistical tools [22,23]. These markers also demonstrate high heterozygosity [24], rendering them highly suitable for carrying out the present study.

Among the different caste and tribal groups inhabiting the southwest coast of India, we have selected four predominant Dravidian-speaking communities from Karnataka: Iyengar Brahmin, Lyngayat, Gowda and Muslim, they not only belong to dissimilar groups of the Indian caste hierarchy but also have varied migration histories, conferring them uniqueness and significance from a genetic perspective. The present microsatellite study primarily attempts to understand the genetic structure of the four selected populations and to determine their genetic relationship with other linguistically and ethnically similar groups of southern India and Brahmin groups of northern India. It has been suggested that that despite the linguistic homogeneity in southern India, these populations have remained genetically diversified [25]. Hence, we sought to determine the role played by geographical location and linguistic affiliation in genetically differentiating Indian populations. Also, as mentioned earlier, the western coast has witnessed colonization from different world populations, we aim to divulge the impact of these past migrations on the gene pool of the present southern populations by discerning their relationship with historically acclaimed and established migrant groups, ethnically represented by European, Hispanic, East Asian and African populations.

Results
Allele frequency at 15 STR was used to compute the heterozygosity (observed) for the four studied populations, which varied for each locus, and population but reflected similar values, ranging between 0.724 and 0.797 (Table 1). An average GST value of 0.009 elucidates the low degree of genetic differentiation in them. However, the GST value for the pooled Indian and global populations demonstrated a high value at 2.3% (data not shown). Genetic relationship of studied populations with other similar southern groups; Vanniyar, Gounder, Pallar and Tanjore Kallar [26,27], northern Brahmins belonging to Orissa [28] and Bihar [29], and four relevant global ethnic groups: European, Hispanic, African [30] and East Asian [31] was divulged by computing DA distances (Table 2) and represented using NJ tree (Fig. 1). Among the four studied populations, Iyengar, Gowda and Muslim formed a distinct cluster. Although NJ tree clearly depicts the clustering of southern populations, DA distances indicate that among these groups, Iyengar, Lyngayat and Vanniyar are more similar to the northern Brahmins (0.030). Furthermore, genetic distances emphasize the affinity of Lyngayat with Tanjore Kallar (0.029), Iyengar (0.026) and Vanniyar (0.028). Estimation of relatedness between the southern and global populations shows that all the southern communities formed a separate cluster, nevertheless, genetic distances disclose the affinity of upper caste Indian communities; Iyengar, Lyngayat, Vanniyar, Bihar and Oriya Brahmin with Europeans and East Asians. The Indian populations were most distant to Africans.

Table 1 Average heterozygosity and GST values for 15 loci in the four studied populations.

	OBSERVED HETEROZYGOSITY		
			
LOCUS					GST	
	BRAHMIN	LINGAYAT	GOWDA	MUSLIM		
TPOX	0.707	0.581	0.542	0.555	0.010	
D3S1358	0.661	0.793	0.559	0.488	0.036	
THO1	0.815	0.785	0.678	0.688	0.005	
D21S11	0.876	0.857	0.779	0.733	0.005	
D18S51	0.907	0.938	0.779	0.888	0.006	
PENTA E	0.921	0.876	0.864	0.800	0.014	
D5S818	0.692	0.724	0.525	0.733	0.007	
D13S317	0.753	0.714	0.745	0.733	0.007	
D7S820	0.723	0.734	0.754	0.800	0.005	
D16S539	0.861	0.846	0.830	0.777	0.010	
CSF1PO	0.723	0.734	0.745	0.733	0.009	
PENTA D	0.815	0.755	0.741	0.933	0.006	
vWA	0.784	0.734	0.779	0.688	0.002	
D8S1179	0.861	0.822	0.745	0.755	0.007	
FGA	0.861	0.894	0.803	0.911	0.017	
Average	0.797	0.785	0.724	0.747	0.009	
Table 2 DA distance matrix between ten Indian and four global groups based on allele frequency at 15 microsatellites.

Pop	HS	NE	MO	CA	OB	IB	LY	GO	MU	BB	PL	VN	TK	GD	
HS															
NE	0.079														
MO	0.049	0.123													
CA	0.029	0.086	0.07												
OB	0.044	0.092	0.052	0.04											
IB	0.044	0.091	0.041	0.04	0.03										
LY	0.047	0.096	0.047	0.04	0.03	0.026									
GO	0.066	0.122	0.072	0.07	0.055	0.036	0.047								
MU	0.076	0.118	0.078	0.07	0.066	0.051	0.056	0.054							
BB	0.043	0.101	0.052	0.05	0.038	0.031	0.037	0.054	0.068						
PL	0.061	0.11	0.067	0.07	0.064	0.05	0.056	0.075	0.077	0.063					
VN	0.045	0.105	0.042	0.04	0.034	0.023	0.028	0.039	0.053	0.037	0.049				
TK	0.047	0.096	0.053	0.05	0.044	0.028	0.029	0.052	0.062	0.044	0.052	0.032			
GD	0.064	0.112	0.064	0.06	0.051	0.036	0.043	0.057	0.073	0.054	0.059	0.032	0.043		
Abbreviations used in Table- Hispanic – HS, African – AF, Asian – AS, European – EU, OriyaBrahmin – OB, Iyengar Brahmin – IB, Lyngayat – LY, Gowda – GO, Muslim – MU, Bihar Brahmin – BB, Pallar – PL, Vanniyar – VN, Tanjore Kallar – TK, Goundar – GD.

Figure 1 Neighbor-joining tree depicting the genetic relationship of Karnataka populations with related Indian and global ethnic groups based on 15 STR markers.

The regression model (Fig. 2), of mean per locus heterozygosity against distance from centroid assumes that when a population experiences same amount of gene flow from a homogenous source, a linear relationship exists between the expected and observed heterozygosity. A change in gene flow directly affects this linear relationship. The R-matrix when applied to the Indian populations assists in understanding the influence of external gene flow and admixture among populations. The higher observed than expected heterozygosity of Iyengar and Lyngayat, placed above the theoretical regression line helps infer that these populations have received more than average external gene flow, which was also observed in Vanniyar, Pallar and Oriya Brahmin. The Gowda and Muslim groups exhibit lower than expected heterozygosity values and fall below the regression line, suggesting lesser admixture in them.

Figure 2 Regression plot demonstrating the relatively higher gene flow levels in high-ranking populations of India. Abbreviations used in figure: OB-Oriya Brahmin, PL-Pallar, IB-Iyngar Brahmin, VN-Vanniyar, LY-Lyngayat, TK-Tanjorekallar, GD-Goundar, Mu-Muslim, BB-Bihar Brahmin, GO-Gowda.

The microsatellite diversity computed using AMOVA revealed that the genetic variation observed in Indian populations was mainly confined to variation amongst individuals (~98%), irrespective of their geographic or linguistic grouping (Table 3). The geographical clustering of populations into three regions: north, southwest (Karnataka) and southeast (Tamil Nadu) demonstrated a low variance of 0.29%, p = 0.010 (Table 3a). As compared to geographical grouping, the linguistic clustering (Indo-Caucasian and Dravidian) exhibited a noticeable increase in the molecular variance between the two groups, 0.65% (p = 0.06, Table 3b). The genetic diversity among populations within each group remained almost similar at both levels of analysis.

Table 3 Genetic differentiation of Indian populations based on AMOVA

(a) Geographical grouping			
Groups in set 1	Source of Variation	Percentage Variation	
	
Group 1 – North: Bihar and Orissa populations	Among groups	0.29	
Group 2 – South-west: Karnataka populations	Among populations in groups	0.97	
Group 3 – South-east: Tamil Nadu Populations	Within populations	98.74	
(b) Linguistic grouping			
	
Groups in set 2	Source of Variation	Percentage Variation	
Group 1 – Indo-European: Orissa and Bihar	Among groups	0.69	
Group 2 – Dravidian: Southern populations	Among populations in groups	0.94	
	Within populations	98.40	
Discussion
In recent years, population genetics has witnessed extensive use of microsatellite markers to understand and evolutionary histories of contemporary human populations [17,32-34]. Though, the populations inhabiting south India have played a major role in formation of the Indian gene pool, however, very few genetic studies have been carried out on them. The present study utilizes 15 STRs to provide comprehensive genetic information on four predominant communities inhabiting the southwest coast of India, which may significantly help in understanding the genetic composition of southern populations.

Genetic structure of Karnataka populations
The most distinctive feature revealed by the fifteen microsatellites was the considerable genetic homogeneity amongst the four diverse caste groups residing in southwest India. The presence of an almost similar allele frequency pattern [34], suggests that these populations might have a common ancestry or probably experienced very high gene flow during the period of their coexistence. The above finding is further supported by the low genetic differentiation of 1.0% among the studied groups irrespective of their caste and migration histories. The high heterozygosity and rii values in Lyngayat reflect the admixture and stochastic processes experienced by it. The genetic affinity of Lyngayat with other related southern caste populations, like, Iyengar, Vanniyar and Tanjore Kallar reiterates its heterogeneous past. It is noteworthy that although the southern populations exhibited higher affinity amongst each other, the high-ranking populations, like, Iyengar, Lyngayat and Vanniyar also displayed some genetic similarity to Brahmins from Bihar and Orissa, indicating that the gene pool of Iyengar and Lyngayat probably consists of genetic inputs from both southern and northern groups. However, strong conclusions cannot be drawn due to low genetic differentiation among the studied populations. Though the Gowda is known to have moved in to Karnataka from the adjoining area of Tamil Nadu, our study reveals that Gowda cluster with the studied populations and not with Tamil groups. The low hetetozygosity and high rii values of Gowda implies that it might have differentiated as a result of stochastic processes. Furthermore, the relatively lower heterozygosity and admixture levels of Gowda and Muslim might be attributed to the socio-cultural practice of consanguineous marriages in them. The Muslim group was found to be genetically similar to local populations. Regional conversions from diverse castes that occurred during the period of Islamic dominance might elucidate the more or less identical genetic relationship between Muslims and other studied groups. The microsatellite study emphasizes the genetic similarity among the Karnataka populations, with the lack of any strong caste or religious bias in them.

Analysis of genetic variance
AMOVA test strongly suggests that genetic diversity among the southern populations was mainly confined to intra-population variation, further emphasizing the genetic homogeneity in them. Analysis using different genetic markers corroborate with our finding that the genetic diversity in human populations can be mainly attributed to variation within populations [4,17,19,34,36,37].

An exploration of the genetic differentiation based on geographical grouping of populations discloses the genetic similarity among populations residing in a region. Nevertheless, the geographic affinity was comparably lesser to that observed within the two linguistic families, viz., Dravidian and Indo-European. Our finding provides evidence to the strong linguistic affinity prevailing amongst the Dravidian speaking populations and imparts them genetic distinctness from the Indo-European linguistic group. Even though prior studies have indicated that genetic clusters often correspond closely to predefined regional and linguistic groups [34], AMOVA suggests that caste system along with geographical contiguity are not ideal platforms for differentiating the analyzed Indian populations. It must, however, be acknowledged that use of less number of polymorphisms in this study might plausibly have led to the greater influence of linguistic affiliation on these populations rather than geographical proximity.

Genetic affinity with global populations
The genetic differentiation of the studied populations with relevant global migrant groups was estimated to be 2.3%, relatively lower than the 9% observed in another similar study [16], which had used a different set of microsatellite markers. Sampling from a confined area, as well as the use of lesser number of loci might have contributed to this apparent difference in the results. The southern populations formed a separate cluster from the world populations. Molecular studies on Indian populations using diverse markers (nuclear, mtDNA and Y-chromosome) have demonstrated that the upper caste populations have higher semblance with Europeans than Asians [26]. Intriguingly, in the present study, communities belonging to the upper strata of the Hindu caste hierarchy, i.e., Iyengar, Lyngayat, Vanniyar and northern Brahmins, displayed almost identical genetic affinity with both Europeans and East Asians. Therefore, all though it is believed that south India remained isolated and cushioned from the foreign invasions, the southern populations, especially, the high-ranking groups might have genetically admixed with migrant groups that entered via the west coast and north. Further exploration of their relationship is essential before drawing concrete conclusions. A more comprehensive picture would emerge on analysis of mtDNA and Y chromosome markers.

Methods
The populations
The populations selected in this study comprise of three major Hindu castes-Iyengar, Lyngayat, Gowda and a Muslim community, inhabiting the southwest coastal terrain of Karnataka (11.3 – 18.45°N latitudes and 74.12 – 78.40°E longitudes). All the populations belong to the Dravidian linguistic family and are speakers of the local dialect, Kannada, but differ in caste hierarchy and socio-religious practices. Consanguineous marriages have been reported in Karnataka, with inbreeding levels of the order 0.020 to 0.033, in general [38].

Iyengar hold a high position in the Indian caste hierarchy and sporadic accounts on Brahmin, suggests that they primarily migrated from the upper Gangetic plains to southern India. Nonetheless, few bioanthropological studies have revealed that morphologically Brahmins of a geographical region are similar to the local groups.

Lyngayat community was initially formed, as a religious cult by the amalgamation of people from different castes and geographical regions but later developed into a distinct community practicing strict marriage endogamy with social sub-divisions such as clans, sub-castes and sects [10].

Gowda is a low ranking agriculturist caste group that typically exhibits the Dravidian socio-cultural characteristic of consanguineous marriage. It is believed to have moved in from the adjoining area of Tamil Nadu.

Muslim is a linguistically heterogeneous, complex religio-ethnic group, [10]. It is believed that the invasion of Turks, Afghans (A.D 998–1030) and Moghals during the 15th century, introduced new genes only in northern India, suggesting that Muslims from Southern India are mainly local converts [3].

Micosatellite loci studied
The 15 STR marker set analyzed in this study consists of thirteen tetra nucleotide repeat loci: D3S1358, THO1, D21S11, D18S51, D5S818, D13S317, D7S820, D16S539, CSF1PO, vWA, D8S179, TPOX, FGA and two penta nucleotide repeat loci: Penta D, Penta E. Their repeat size makes them less prone to slippage of polymerase during enzymatic amplification compared to the dinucleotide repeats, allowing unambiguous typing [20]. The 15 selected loci are situated on 13 different chromosomes, with D5S818 and CSF1PO being present on chromosome 5 and Penta D and D21S11, located on chromosome 21. The alleles across the loci are substantially unlinked, making them suitable for analyzing inter and intra-population genetic diversity.

STR Typing
The blood samples were collected from unrelated individuals belonging to – Iyengar (65), Lyngayat (98), Gowda (59) and Muslim (45) communities, residing in different districts of Karnataka. DNA was extracted from blood by the phenol-chloroform method [40], followed by quantitation using the QuantiBlot™ kit (Perkin-Elmer, Foster City, CA, USA). Two nanogram of the isolated DNA was used as template for the PCR amplification of the 15 STRs using the PowerPlex™16 kit (Promega Corp., Wisconsin Madison, USA). Raw data were collected with the GeneScan™ software, Ver. 3.2.1 (Applied Biosystems, Foster City, CA, USA) and typed using the PowerTyper™ 16 Macro (Promega Corp., Wisconsin Madison, USA).

Statistical Analysis
Allele frequencies of the 15 STR loci were calculated using the gene counting method [40]. The genetic diversity (GST), observed heterozygosity and pairwise genetic distances (DA) were computed using allele frequencies [42]. The DA distance is least affected by sample size and can precisely obtain correct phylogenetic trees under various evolutionary conditions [43]. Neighbor-joining trees were constructed using DA distances [44], and its robustness was established by bootstrap resampling procedures.

Analysis of molecular variance (AMOVA) was performed using the Arlequin Ver. 2.00 package [45]. Two levels of analysis were performed to explore the microsatellite diversity among the four studied populations along with six other socio-culturally similar groups inhabiting different regions of India. At the first level, three geographical groups were constructed: (1) north (2) southwest: Karnataka and, (3) southeast: Tamil Nadu, to estimate the genetic variance among populations from diverse geographical regions. The second set of analysis was aimed at investigating the genetic diversity between the Dravidian and Indo-European linguistic family.

To assess the gene flow experienced by these populations, the rii value, i.e., the genetic distance of a population from the centroid was calculated using the regression model [46]. This model utilizes the heterozygosity of each population and the distance from the centroid as the arithmetic mean of allele frequencies:



where, rii is the distance from the centroid, pi is the frequency of the allele in ith population and  is the mean allelic frequency.

List of abbreviations
STR – Short Tandem Repeat

AMOVA – Analysis of Molecular Variance

NJ tree – Neighbor-Joining tree

Authors' contributions
RR carried out the molecular studies, analyzed the genetic data and drafted the manuscript. VKK participated in the design, conceiving and preparation of manuscript. Both authors read and approved the final manuscript.

Acknowledgements
This work was supported by a research grant under the IX Five Year Plan to CFSL, Kolkata and a research fellowship from the Ministry of Home Affairs to the first 1 author. The technical assistance of Dr. R Trivedi is highly appreciated. This work would not have been possible without the co-operation of volunteers of blood samples used for genotyping in the study. The comments of two anonymous reviewers' were extremely helpful in improving the text of the paper.
==== Refs
Cann RL  Genetic clues to dispersal in human populations: Retracing past from the present Science 2001 291 1742 1748 11249820 10.1126/science.1058948 
Majumder PP  People of India: Biological diversity and affinities Evolutionary Anthropology 1998 6 100 110 10.1002/(SICI)1520-6505(1998)6:3<100::AID-EVAN4>3.0.CO;2-I 
Papiha SS  Genetic variation in India Hum Biol 1996 68 607 628 8908794 
Roychoudhury AK  Genetic relationships of the populations of eastern India Ann Hum Biol 1992 19 489 501 1510344 
Mastana SS Papiha SS  Genetic variability of transferring subtypes in the populations of India Hum Biol 1998 70 729 44 9686483 
Mountain JL Hebert JM Bhattacharyya S Underhill PA Ottolenghi C Gadgil M Cavalli-Sforza LL  Demographic history of India and mt.DNA-sequence diversity Am J Hum Genet 1995 56 979 92 7717409 
Sundra A  The early chamber tombs of south India 1975 New Delhi: University Publishers 
Cavalli-Sforza LL Menozzi P Piazza A  The history and geography of human genes 1994 Princeton, NJ: Princeton University Press 
Gadgil M Joshi NV Shambu Prasad UV Manmohan S Suresh Patil  Balasubramanian D, Rao D  Peopling of India 1997 The Indian Human Heritage Hyderabad: University Press 
Singh KS  India's communities national series people of India 1998 New Delhi: Oxford University Press 
Banerjee S Roy M Dey B Mukherjee BN Bhattacharjee SK  Genetic polymorphism of red cell antigen, enzyme, haemoglobin and serum protein in fifteen endogamous groups of south India J Indian Anthropol Soc 1988 23 250 262 
Walter H Naide JM Danker-Hopfe H de Beck M Harms M Babu BV Yasmin  Devi SS  Genetic serum protein markers in eight south Indian caste and tribal populations Z Morphol Anthropol 1993 79 355 65 8128763 
Mukherjee BN Reddy AP Malhotra KC Vijaykumar M  Patterns of social and geographical distribution of transferrin subtype polymorphism in India Hum Hered 1986 36 113 118 3699837 
Vijayakumar M Malhotra KC Walter H Gilbert K Linderberg P Dannewit A Sorensen A Chakraborty R Reddy AP Mukherjee BN  Genetic studies among the Siddis of Karnataka, India: a migrant population from Africa Z Morphol Anthropol 1987 77 97 121 3445677 
Dutta R Kashyap VK  Genetic variation observed at 3 tetrameric STR loci HumTHO1, TPOX, and CSF1PO in 5 ethnic population groups of northeastern India Am J Hum Biol 2001 13 23 29 11466963 10.1002/1520-6300(200101/02)13:1<23::AID-AJHB1003>3.3.CO;2-I 
Dutta R Reddy BM Chattopadhyay P Kashyap VK Sun G Deka R  Patterns of Genetic Diversity at the 9 forensically approved STR loci in the Indian populations Hum Biol 2001 74 33 49 11931578 
Deka R Shriver MD Yu LM Herdreich EM Jin L Zhong Y McGarvey ST Agarwal SS Bunker CH Miki T Hundrieser J Yin S Raskin S Barrantes R Ferrell RE Chakraborty R  Genetic variation at twentythree microsatellite loci in sixteen human populations Journal of genetics 1999 78 99 121 
Chu JY Huang W Kuang SQ Wang JM Xu JJ Chu ZT Yang ZQ Lin KQ Li P Wu M Geng ZC Tan CC Du RF Jin L  Genetic relationship of populations in China Evolution 1998 95 11763 11768 10.1073/pnas.95.20.11763 
Reddy MB Sun G Luis JR Crawford MH Heman NS Deka R  Genomic diversity at 13 STR loci in a substructured caste population, Golla, of southern Andhra Pradesh, India Human Biology 2001 73 175 190 
Mukherjee N Majumder PP Roy B Roy M Chakraborty M Banerjee S  Variation in 4 short tandem repeat loci in 8 population groups of India Hum Biol 1999 71 439 446 10380378 
Destro-Bisol G Boschi I Caglia A Tofanelli S Pascali V Paoli G Spedini G  Microsatellite variation in central Africa: An analysis of Intrapopulation and interpopulation genetic diversity Am J Phys Anthropol 2000 112 319 337 10861350 10.1002/1096-8644(200007)112:3<319::AID-AJPA4>3.0.CO;2-F 
Dib C Faure S Fizames C Samson D Drouot N Vignal A Millasseaur P Marc S Hazan J Seboun E Lathrop M Gyapay G Morissette J Meissenbach J  A comprehensive genetic map of the human genome based on 5,624 microsatellites Nature 1996 380 152 154 8600387 10.1038/380152a0 
Zhivotorsky LA Feldman MW Grishechkin SA  Biased mutation and microsatellite variation Mol Biol Evol 1997 14 926 933 9287425 
Kimmel M Chakraborty R King JP Bamshad M Watkins WS Jorde LB  Signatures of population expansion in microsatellite repeat data Genetics 1998 148 1921 1930 9560405 
Majumder PP  Macer DRJ  Genes, diversities and peoples of India In Ethical challenges as we approach the end of the human genome project 1998 Eubios Ethics Institute 20 33 
Sitalaxmi T Trivedi R Kashyap VK  Genotype profile for thirteen tetranucleotide repeat loci and two pentanucleotide repeat loci in four endogamous Tamil population groups of India J Forensic Sci, USA 2002 47 1168 1173 
Sitalaxmi T Trivedi R Kashyap VK  Autosomal microsatellite profile of 3 socially diverse ethnic Tamil populations of India J Forensic Sci, USA 2003 47 211 214 
Sahoo S Kashyap VK  Allele frequencies of data for Powerplex 16 loci in four major populations of Orissa, India J Forensic Sci, USA 2002 47 912 915 
Ashma R Kashyap VK  Genetic study of 15 important STR loci among four major ethnic groups of Bihar, India J Forensic Sci, USA 2002 47 1139 1142 
Levedakou EN Freeman DA Budzynski MJ Early BE McElfresh KC Schumm JW Amin AS Kim YK Sprecher CJ Krenke BE Silva DA McIntosh TM Grubb JC Johnston LJ Sailus JS Ban JD Crouse CA Nelson MS  Allele Frequencies for fourteen STR Loci of the PowerPlex™ 1.1 and 2.1 Multiplex Systems and Penta D Locus In Caucasians, African-Americans, Hispanics, and Other Populations of the United States of America and Brazil J Forensic Sci, USA 2001 46 423 767 
Law MY To KY Ho SH Pang BCM Wong LM Wun SK Chan KL  STR data for the PowerPlex™ 16 loci for the Chinese population in Hong Kong Forensic Sci Int 2002 129 64 67 12230999 10.1016/S0379-0738(02)00169-X 
Calafell F Shuster A Speed WC Kidd KK  Short tandem repeat polymorhism evolution in humans Eur J Hum Genet 1998 6 38 49 9781013 10.1038/sj.ejhg.5200151 
Bosch E Calafell F Perez-Lezaun A Clarimon J Comas D Mateu E Martinez-Arias R Morera B Brakez Z Akhayat O Sefiani A Hariti G Cambon-Thomsen A Bertranpetit J  Genetic structure of north-west Africa revealed by STR analysis Eur J Hum Genet 2000 8 360 366 10854096 10.1038/sj.ejhg.5200464 
Rosenberg NA Pritchard JK Weber JL Cann HM Kidd KK Zhivotovsky LA Feldman MW  Structure of human populations Science 2002 298 2381 2385 12493913 10.1126/science.1078311 
Rajkumar R Kashyap VK  Distribution of alleles of fifteen STR loci of the Powerplex 16 multipex in four predominant population groups of south India Forensic Sci Int 2002 126 175 179 
Mastana SS Reddy PH Das MK Das K  Molecular genetic diversity in 5 populations of Madhya Pradesh, India Human Biol 2000 72 499 510 10885195 
Pandey BN Das PKL Pankaj PK Vasulu TS  Genetic diversity and population structure among 13 endogamous populations of Purnis, Bihar The mankind Quaterly 2000 40 355 380 
Bittles AH Coble JM Rao NA  Trends in consanguineaous marriage in Karnataka, south India, 1980–89 J Biosoc Sci 1993 25 111 6 8425878 
Bamshad M Kivisild T Watkins WS Dixon ME Ricker CE Rao BB Naidu JM Prasad ME Reddy PG Rasanayagam A Papiha SS Villems R Reddy AJ Hammer MF Nguyen SV Carroll ML Batzer MA Jorde LB  Genetic evidence on the origins of Indian caste populations Genome Research 2001 11 994 1004 11381027 10.1101/gr.GR-1733RR 
Sambrook J Fritsch EF Maniatis T  Ford N, Nolan C, Ferguson MC  Molecular cloning: A laboratory manual 1989 Cold Spring Harbor: Cold Spring Harbor Laboratory Press 
Li CC  First course in population genetics 1976 C A: Boxwood 
Nei M Tajima F Tateno Y  Accuracy of estimated phylogenetic trees from molecular data J Mol Evol 1983 19 153 170 6571220 
Takazaki N Nei M  Genetic distances and reconstruction of phylogenetic trees from microsatellite DNA Genetics 1996 144 389 399 8878702 
Saitou N Nei M  The neighbor-joining method: A new method for reconstrusting phylogenetic trees Mol Biol Evol 1987 4 406 425 3447015 
Schneider S Roessli D Excoffier L  Arlequin ver 2.000: A software for population genetic analysis Genetics and Biometry Laboratory, University of Geneva, Switzerland 2000 
Harpending HC Ward R  Nitecki M  Chemical systematics and human evolution In Biochemical aspects of evolutionary biology 1982 IL: University of Chicago Press 213 256

