Genetic markers among Meiteis and Brahmins of Manipur, India

Prevalence of β-Thalassemia and hemoglobin E in two migrant populations of Manipur, North East India

Hemoglobinopathies are a group of inherited single-gene disorders found commonly in the Mediterranean region, Middle East, Indian subcontinent, Burma, and South East Asia. As many as 229 mutation variants of β-thalassemia are reported in the world, many community/region-specific mutations. Very little on thalassemia has been reported in Manipur, a North Eastern Indian state. Thus, a community genetic approach through population screening can be applied to the people of Manipur and a total of 602 blood samples from unrelated Meitei Brahmins (n=300) and Meitei Muslims (n=302) were screened for abnormal hemoglobins by Naked Eye Single Tube Red Cell Osmotic Fragility Test (NESTROFT). HBA(2) level was estimated by using high-performance liquid chromatography and molecular analysis was done by using PCR. Sequencing was also carried out to confirm the mutations. High frequencies of NESTROFT positive (10%) and NESTROFT doubtful (11%) cases were found among the Meitei Brahmins in comparison to the Meitei Muslims [NESTROFT positive (3.31%) and NESTROFT doubtful (1.33%)]. The allele frequency of HB*E was 0.022 and 0.012 among the Meitei Brahmin and Meitei Muslim, respectively. Sequencing of the β-globin gene confirmed a very rare β-thalassemia [-90 C→T (0.33%)] among the Meitei Brahmins of Manipur. This mutation with hemoglobin E in one of the present population hints the presence of the Mongoloid stock among them, possibly from China. There is a need for further studies on other populations of Manipur and the neighboring North East Indian states using such genetic markers.

Genetic heterogeneity in northeastern India: reflection of Tribe-Caste continuum in the genetic structure

We critically examined the gene frequency data for 11 genetic markers commonly available in the literature for 22 populations of northeastern India in the light of their geographic, linguistic, and ethnic affiliations. The markers investigated were three blood groups (A1A2BO, MNS, and Rh), four serum proteins (KM, Gc, Hp, and Tf), and four enzyme systems (AP, AK, EsD, and Hb). The neighbor-joining tree and multidimensional scaling of the distance matrix suggest relatively high genetic differentiation among the Mongoloid groups, with probably diverse origins when compared to the Caucasoid Indo-European populations, which had probably come from relatively more homogeneous backgrounds. Broadly speaking, the pattern of population affinities conforms to the ethno-historic, linguistic, and geographic backgrounds. An interesting and important feature that emerges from this analysis is the reflection of the effect of the sociological process of a Tribe-Caste continuum on genetic structure. While on one end we have the cluster of Caucasoid caste populations, the other end consists of Mongoloid tribal groups. In between are the populations which were originally tribes but now have become semi-Hinduized caste groups, viz., Rajbanshi, Chutiya, and Ahom. These groups have currently assumed caste status and speak Indo-European languages. Therefore, one may infer that what appears to be a purely sociological phenomenon of a Tribe-Caste continuum may well reflect in their genetic structure.

Khmers of Cambodia: A comparative genetic study of the populations of Southeast Asia

A sample of the Khmer population from Cambodia has been examined for 30 single-gene characters (10 blood groups and 20 serum and red cell systems). A locus-by-locus comparison suggests that the Khmers differ significantly in several systems from the populations of Eastern India and China. There is remarkable heterogeneity among their geographical neighbors. To elucidate the genetic relationship of the Khmer, genetic data were collected from various published and unpublished sources, and different multivariate analyses were performed. The analyses show that the Khmers definitely show closer affinity for the neighboring populations of Thailand and Malaysia. The Chinese population not only shows a close relationship to the Khmers, but also consistently stays close to the populations of the Southeast Asian peninsula. The present-day Khmers are genetically distant from the population of Eastern India, but the analyses do not totally exclude gene flow from Eastern India. It is, therefore, concluded that the original gene pool of Khmers may have derived from China, being modified by mixing with the local and Indian migrant populations. © 1994 Wiley-Liss, Inc.

Genetic relationships of the populations in eastern India

The genetic relationships for four sets of populations in eastern India have been studied by using gene frequency data available in the literature. The Caucasoid populations in Assam and West Bengal are genetically close but different from the Mongoloid populations in the neighbourhood. The genetic distance analysis shows that the Mongoloid populations in Assam and West Bengal cluster according to their states of residence, indicating a correlation between genetic and geographical distances.

Genetic studies among the Nagas and Hmars of eastern India

A total of 148 Nagas (65 urban and 83 rural) and 81 Hmars from northeastern India were tested for 15 blood genetic markers. Both the Nagas and Hmars lacked haemoglobin variants and G6PD deficiency and had a high frequency of PGDC. This may be attributed to selective pressures operating at these loci. Genetic distance estimates using 41 alleles at 11 polymorphic loci showed appreciable heterogeneity between the urban and rural Nagas that were in line with the differences in gene frequencies. Considerable genetic admixture of the urban Nagas from the Hmar and other neighbouring populations is evident. The Nagas were found to be quite distant from the mainland Han Chinese and Malays as well as from the Bengalis and Oraons. However, they appear to be related to the Hmar and Lepcha. Evidence supporting the ethnohistoric origin of the Nagas from China or the South Seas is lacking.

Serogenetic investigations of Tibetans and Himachalis from Himachal Pradesh, India: genetic relationship between Tibetans and certain selected mongoloid populations

Twenty two serogenetic systems were investigated in 115 Tibetans and 128 Himachalis from the state of Himachal Pradesh, northwest India. For eight of the loci (ABO, Rh, MNSs, P, Fy, 6PGD, EsD, and AK) the two populations showed conclusive heterogeneity and their frequency distribution showed that the serogenetic differences between two populations are due to their different racial affiliations. The Tibetans were also analysed for their genetic relationship with certain selected populations from the Cis-Himalayan, far east and south Asian regions. The calculations of the Harpending's kinship matrix R and the genetic distances showed that the Tibetans are closer to the mongoloid populations of the Cis-Himalayan region and the differences in the present day population structure of the mongoloid groups of this region are more likely to be due to differential migration, admixture and racial affiliation although there is a slight possibility of disruptive selection for certain loci such as 6PGD and AK which showed an exceptionally high value of Canning (6PGD*C) and AK*1 genes.

Immunoglobulin (Gm and Km) allotypes in nine endogamous groups of West Bengal, India

Blood samples from 898 individuals of nine endogamous groups of West Bengal, India were typed for determining the haplotypic structure in the gamma-light chain (Gm) and kappa-light chain (Km) of immunoglobulin (IgG). The Gm haplotype frequencies detected by Glm (1), Glm (2) and G3m (5) markers suggest that in this eastern state of India there is considerable variation of frequencies of the typical Mongoloid haplotype Gm1,5, which shows a high incidence in Rajbanshi, Rabha, Garo and Lodha groups. On the contrary, this haplotype is probably absent in the high caste groups, Rarhi Brahmin and Vaidya, and is relatively infrequent in Jalia Kaibarta, a scheduled caste of the south-western part of the state. The Km1 allele is also high in frequency among Rajbanshi, Rabha, Garo and Munda in comparison with Rarhi Brahmin and Vaidya, suggesting the former four groups' strong Mongoloid affiliation. This survey signifies that there is considerable variation in the extent of Mongoloid admixture in Bengali populations. Such admixture is not restricted in specific social class either. It further demonstrates that heterogeneity of the genetic structure of Bengali populations do not correspond to the present social ranking on the basis of caste hierarchy.