Birajalaxmi Das

Minimal Sharing of Y-Chromosome STR Haplotypes Among Five Endogamous Population Groups from Western and Southwestern India

We attempt to address the issue of genetic variation and the pattern of male gene flow among and between five Indian population groups of two different geographic and linguistic affiliations using Y-chromosome markers. We studied 221 males at three Y-chromosome biallelic loci and 184 males for the five Y-chromosome STRs. We observed 111 Y-chromosome STR haplotypes. An analysis of molecular variance (AMOVA) based on Y-chromosome STRs showed that the variation observed between the population groups belonging to two major regions (western and southwestern India) was 0.17%, which was significantly lower than the level of genetic variance among the five populations (0.59%) considered as a single group. Combined haplotype analysis of the five STRs and the biallelic locus 92R7 revealed minimal sharing of haplotypes among these five ethnic groups, irrespective of the similar origin of the linguistic and geographic affiliations; this minimal sharing indicates restricted male gene flow. As a consequence, most of the haplotypes were population specific. Network analysis showed that the haplotypes, which were shared between the populations, seem to have originated from different mutational pathways at different loci. Biallelic markers showed that all five ethnic groups have a similar ancestral origin despite their geographic and linguistic diversity.

Population Genetic Analysis among Five Indian Population Groups Using Six Microsatellite Markers

Genetic variation at six tetranucleotide microsatellites (HUMTHO1, HUMVWA, F13A01, D3S1359, D12S66, and D12S67) has been determined in five endogamous ethnic population groups of India belonging to two major linguistic families. The populations analyzed were Konkanastha Brahmins and Marathas (Maharashtra state) from the Indo-Aryan linguistic family and Nairs, Ezhavas, and Muslims (Kerala state) from the Dravidian family. All six loci show high gene diversity, ranging from 0.63 ± 0.04 to 0.84 ± 0.02. The average GST value observed was 1.7%, indicating that the differences between the populations account for less than 2% of the diversity, while the genetic variation is high within the five population groups studied (>98%). The phylogenetic tree fails to show any clear cluster. The absence of any cluster along with low average GST is suggestive of substantial genetic similarity among the studied populations, in spite of clear geographical, linguistic, and cultural barriers. This similarity indicates either a greater gene flow between these groups or, alternatively, may reflect a recent evolution for them, considering that the Indian caste system evolved only about 3000 years ago.

Y-chromosomal STR haplotypes in two population groups of Kerala in south India.

Via electronic mail from communicating author. Analysis of Data: Haplotype diversities and frequencies were calculated by using the program ARLEQUIN l. l (4). The nomenclature of the allele sizes was as described by Kayser et al. (2) except for DYS389I and DYS38911, which was according to Cooper et al. (5).

Population data of two minisatellite loci (D1S80 and D17S5) among five distinct ethnic groups of India.

Population Data of Two Minisatellite Loci (D1S80 and D17S5) Among Five Distinct Ethnic Groups of India

Allele frequency distribution at five Y-chromosomal short tandem repeat loci among five distinct ethnic groups of India.

Genomic DNA was extracted using a rapid non-enzymatic method (1). The PCR primers and the parameters for PCR amplification of all the five Y-chromosomal STRs were as described by Kayser et al. (2) and de Knijff et al. (3). The forward primer of each locus was labeled with flourescent CY5™ dye amidite (Amersham Pharmacia Biotech) and PCR was carried out in a Hybaid™ thermal cycler using Taq polymerase (Roche Molecular Biochemicals). Amplimers were electrophoresed in 6% denaturing urea gel (7M) and analyzed by fragment manager using ALF Express DNA Sequencer (Amersham Pharmacia Biotech). Internal ladders were used for the accurate size determination. Allelic ladders were prepared for each locus and used as external standards in addition to CY5™ labelled 50 to 500 bp DNA ladder (Amersham Pharmacia Biotech). At each locus, the amplimers were compared with the standards, kindly supplied by Dr. Chris Tyler-Smith from Oxford University, Oxford, UK, for confirmation.

Molecular genetic data at two tetranucleotide repeat loci (D12S66 and D12S67) in two Indian tribal populations.

Molecular genetic polymorphism study was undertaken in two tribal population groups of India at two tetranucleotide repeat loci on chromosome 12 (D12S66 and D12S67). The two tribal groups studied were Bison Horn Maria and Muria, belonging to Bastar district of Madhya Pradesh in Central India. For this study, 75 random, unrelated individuals were analyzed for D12S66 locus, whereas 76 individuals were analyzed for D12S67 locus.

Molecular genetic analysis of TPO and CD4 loci among two endogamous ethnic groups of Maharashtra in Western India.

Molecular genetic polymorphism study was undertaken in two endogamous ethnic groups of Maharashtra in Western India at two microsatellites i.e., TPO, a tetranucleotide repeat locus and CD4, a pentanucleotide repeat locus. The two ethnic groups studied were Konkanastha Brahmins and Marathas belonging to Indo-European language family. Eighty-two random, unrelated individuals were genotyped for the locus TPO, whereas for CD4 locus, 79 individuals were genotyped.