Genetic studies on Gadaba: a tribal population of Andhra Pradesh, India.

Blood samples were collected from Gadaba, a tribal population of Andhra Pradesh, South India, in order to examine the distribution of blood groups, red cell enzymes and the gammaglobulin polymorphism. Out of 20 genetic markers studied seven protein loci exhibited monomorphism. Surprisingly a case of a rare homozygous variant and twenty-one heterozygous variants at the phosphogluconate dehydrogenase locus (6-PGD), six variants at the phosphohexose isomerase locus (PHI) and a single case of phosphoglucomutase locus 1 (PGM 1) variant were observed. Further, the tribal populations of South India reveal higher frequencies of rare variants than the caste populations. However, the presence of rare variants that are phenotypically neutral may be plausibly due to their high selective value.

Detection of a new variant phenotype of phosphohexose isomerase in the Gadaba tribe of Andhra Pradesh, south India.

A total of 998 unrelated individuals from the Gadaba tribal population of Andhra Pradesh, South India, were screened for red cell phosphohexose isomerase (PHI) by starch gel electrophoresis. A new and hitherto for Andhra Pradesh not yet reported rare variant phenotype was observed: PHI 6-1. The new allele is designated as PHI*6Gadaba.

mtDNA variation in caste populations of Andhra Pradesh, India.

Various anthropological analyses have documented extensive regional variation among populations on the subcontinent of India using morphological, protein, blood group, and nuclear DNA polymorphisms. These patterns are the product of complex population structure (genetic drift, gene flow) and a population history noted for numerous branching events. As a result, the interpretation of relationships among caste populations of South India and between Indians and continental populations remains controversial. The Hindu caste system is a general model of genetic differentiation among endogamous populations stratified by social forces (e.g., religion and occupation). The mitochondrial DNA (mtDNA) molecule has unique properties that facilitate the exploration of population structure. We analyzed 36 Hindu men born in Andhra Pradesh who were unrelated matrilineally through at least 3 generations and who represent 4 caste populations: Brahmin (9), Yadava (10), Kapu (7), and Relli (10). Individuals from Africa (36), Asia (36), and Europe (36) were sampled for comparison. A 200-base-pair segment of hypervariable segment 2 (HVS2) of the mtDNA control region was sequenced in all individuals. In the Indian castes 25 distinct haplotypes are identified. Aside from the Cambridge reference sequence, only two haplotypes are shared between caste populations. Middle castes form a highly supported cluster in a neighbor-joining network. Mean nucleotide diversity within each caste is 0.015, 0.012, 0.011, and 0.012 for the Brahmin, Yadava, Kapu, and Relli, respectively. mtDNA variation is highly structured between castes (GST = 0.17; p < 0.002). The effects of social structure on mtDNA variation are much greater than those on variation measured by traditional markers. Explanations for this discordance include (1) the higher resolving power of mtDNA, (2) sex-dependent gene flow, (3) differences in male and female effective population sizes, and (4) elements of the kinship structure. Thirty distinct haplotypes are found in Africans, 17 in Asians, and 13 in Europeans. Mean nucleotide diversity is 0.019, 0.014, 0.009, and 0.007 for Africans, Indians, Asians, and Europeans, respectively. These populations are highly structured geographically (GST = 0.15; p < 0.001). The caste populations of Andhra Pradesh cluster more often with Africans than with Asians or Europeans. This is suggestive of admixture with African populations.

Red cell 6-phosphogluconate dehydrogenase polymorphism in the Gadaba of Andhra Pradesh (India). Report of new variant phenotypes.

Blood samples from 1000 unrelated, adult individuals of the Gadaba tribal population were screened for 6-phosphogluconate dehydrogenase. We report the occurrence of a new fast moving variant, which is caused by the allele PGD* Gadaba. This allele is reported for the first time among the tribal populations of Andhra Pradesh. Its frequency comes to 0.0115, and it was observed in heterozygous (2.10%) and homozygous (0.10%) conditions.

Selection intensities and consanguineity in the Yadava and Vadabalija of Visakhapatnam, Andhra Pradesh, India.

The opportunity for intensity of selection is studied in two backward caste groups with different occupations, namely Yadava (pastoral) and Vadabalija (fishing) of Bheemunipatnam Taluk of Visakhapatnam District, Andhra Pradesh. The amount of selection intensity is found to be higher in Vadabalija (0.8583) than Yadava (0.5827). The contribution of mortality to the total index of selection is greater in Vadabalija (0.6095) than in Yadava (0.3326). When consanguineity is considered, the fertility components of selection intensity (0.1885) are lower in the consanguineous group of Yadava than in the nonconsanguineous group (0.2845), whereas in Vadabalija they are higher in the consanguineous group (0.5261) than in the nonconsanguineous group (0.2223).

A note on the age at menarche and its relationship to diet, economic class, sibship size and birth order in 300 Andhra girls.

"This paper reports menarcheal age in a sample of 300 Andhra [India] girls with a view to contribute to the study of secular trend, and attempts to analyse the relationship of menarche to economic status of the family, diet (in broad terms), sibship size and birth order."

Anthropometric variation among Koyas.

Koyas, a tribe of Andhra Pradesh (India) have been studied for anthropometric variation. 15 anthropometric measurements showed significant sex difference.

Distribution of glyoxalase I (GLO) variants in Western Europe and the Indian subcontinent.

English, Italian (including Sardinian), and Spanish populations from Europe and Muslim, Hindu, Sikh, Punjabi, and other populations from the Indian subcontinent currently living either in Birmingham or in India were screened for electrophoretically detectable genetic variants of red cell glyoxalase I (GLO), and their frequencies were reported. All the western European populations investigated, including those reported, exhibited an incidence of close to 44% for the GLO1 gene. The frequency distribution of the GLO1 gene in various populations from the Indian subcontinent, in contrast, was found to range between 0.15 and 0.33. These observations suggest that the European populations in general are genetically more homogeneous than are the populations of the Indian subcontinent.

Red cell glucose-6-phosphate dehydrogenase deficiency among Andhras.

Sixty-eight Andhra males and 45 Andhra females from Visakhapatnam town of Andhra Pradesh, India have been investigated for G-6-PD deficiency. The GdB- gene has a frequency of 4.41% among males. No G-6-PH deficient females were detected. The present data have been compared with the available tribal and non-tribal data from Andhra Pradesh. It is observed that the present sample, though non-tribal in nature, presents a relatively considerable frequency of the GdB- gene.