Natural selection among Kinnaura of the Himalayan highland: A comparative analysis with other Indian and Himalayan populations.

The present investigation on fertility and mortality differential among Kinnaura of the Himalayan highland is based on data collected from 160 post-menopausal women belonging to the middle and high altitude region of Kinnaur district of Himachal Pradesh (Indian Himalayas). Selection potential based on differential fertility and mortality was computed for middle-and high-altitude women. Irrespective of the methodology, the total index of selection was found to be highest among middle-altitude women (0.386) as compared with high-altitude (0.370) women, whereas for the total population it is estimated to be 0.384. It was found that the Kinnaura of the Himalayan highland showing moderate index of total selection and relative contribution of the mortality component (Im) to the index of total selection is higher than the corresponding fertility component (If). The analysis of embryonic and post-natal mortality components shows that the post-natal mortality components are higher in comparison with the embryonic mortality components among highlanders and needs special intervention and health care. The present findings are compared with other Indian tribes as well as non-tribes of the Himalayan region and other parts of the country. It reveals that this index among Kinnaura is moderate than the other population groups; among the Himalayan population, the highest was reported for Galong (It = 1.07) of Arunachal, whereas the lowest was reported from Ahom (It = 0.218) of Manipur. The correlation and regression analysis between total index of selection (It) and fertility (If) and mortality (Im) components for pooled data of populations of the Indian Himalayan states show that If and Im account for 21.6 and 29.1% variability, respectively. In Crow's total index of selection (It) along with strong association, which is significant at the 1% level, this indicates that mortality plays a greater role in natural selection in comparison with fertility among populations of the Indian Himalayas.

Fertility and mortality differentials among selected tribal population groups of north-western and eastern India.

Selection potential based on differential fertility and mortality has been computed for six tribal groups inhabiting different geo-climatic conditions, namely: Sahariya, Mina and Bhil of the State of Rajasthan, north-western India, and Munda, Santal and Lodha of the State of West Bengal, eastern India. Irrespective of the methodology, the total index of selection was found to be highest among Lodhas (0.668), followed by Sahariyas (0.524), Santals (0.462), Bhils (0.386), Mundas (0.353) and Minas (0.334). Incidentally, Lodha and Sahariya are two of the seventy-four notified primitive tribal groups of India, and these two study populations show the highest index of total selection, mainly because of a higher embryonic and postnatal mortality. The relative contribution of the fertility component to the index of total selection is higher than the corresponding mortality component in all tribal groups. The analysis of postnatal mortality components indicates that childhood mortality constitutes the bulk of postnatal mortality, suggesting that children under 5 years need better health care in these tribal groups.

PIP: Selection potential based on differential fertility and mortality has been computed for six tribal groups inhabiting different geoclimatic conditions; namely, the Sahariya, Mina, and Bhil tribes in Rajasthan, northwestern India, and the Munda, Santal, and Lodha tribes in West Bengal, eastern India. Irrespective of the methodology, the total index of selection was found to be highest among the Lodhas (0.668), followed by the Sahariyas (0.524), the Santals (0.462), the Bhils (0.386), the Mundas (0.353), and the Minas (0.334). Incidentally, the Lodhas and Sahariyas are two of the 74 notified primitive tribal groups of India, and these two study populations show the highest index of total selection, mainly because of a higher embryonic and postnatal mortality. The relative contribution of the fertility component to the index of total selection is higher than the corresponding mortality component in all tribal groups. The analysis of postnatal mortality components indicates that childhood mortality constitutes the bulk of postnatal mortality, suggesting that children under age 5 years need better health care in these tribal groups.

Association of genetic markers with coronary heart disease (myocardial infarction)--a case-control study.

A case-control study was carried out on patients of myocardial infarction selected from coronary care unit of Lok Nayak Jai Prakash Narayan Hospital, Delhi. The study was carried out to determine the association of haptoglobin (Hp), transferrin (Tf) and complement component 3 (C3) polymorphism with myocardial infarction. The frequency of allele Hp1 was found to be 0.159 in cases studied and 0.058 in controls. The frequency of gene TfC was found to be 0.987 in cases of study and 0.992 in controls. Similarly, frequency of CS3 gene was found to be 0.985 and 0.990 in cases studied and controls respectively. The comparison between cases studied and controls with respect to TfC and CS3 polymorphism was found to be statistically non-significant while the comparison between cases studied and controls for Hp polymorphism was found to be statistically significant (chi 2 = 21.88, p < 0.01).

Genetic affinities of Sri Lankan populations.

Mythological and historical sketches of the Sri Lankan population indicate that it is heterogeneous and composed of diverse ethnic groups. Ancient chronicles of Sri Lanka relate the origin of the Sinhalese to the legend of Prince Vijaya, who arrived on the northwest coast of the island in 543 B.C. from northeast or northwest India. Further, because Sri Lanka occupies an important position on seaways, it has received a constant influx of people from various parts of the world (especially from the Middle East and Europe), including India. Taking into consideration mythological, historical, and linguistic records of Sri Lanka, I attempt to study the degree of gene diversity and genetic admixture among the population groups of Sri Lanka along with the populations of southern, northeastern, and northwestern India, the Middle East, and Europe. The genetic distance analysis was conducted using 43 alleles controlled by 15 codominant loci in 8 populations and 40 alleles controlled by 13 codominant loci in 11 populations. Both analyses give a similar picture, indicating that present-day Sinhalese and Tamils of Sri Lanka are closer to Indian Tamils and South Indian Muslims. They are farthest from Veddahs and quite distant from Gujaratis and Punjabis of northwest India and Bengalis of northeast India. Veddahs are distinct because they are confined to inhospitable dry zones and are hardly influenced by their neighbors. The study of genetic admixture revealed that the Sinhalese of Sri Lanka have a higher contribution from the Tamils of southern India (69.86% +/- 0.61) compared with the Bengalis of northeast India (25.41% +/- 0.51), whereas the Tamils of Sri Lanka have received a higher contribution from the Sinhalese of Sri Lanka (55.20% +/- 9.47) compared with the Tamils of India (16.63% +/- 8.73). Thus it is apparent that the contribution of Prince Vijaya and his companions, coming from northwest India, to the present-day Sinhalese must have been erased by the long-standing contribution (over 2000 years) of the population groups of India, especially those from Bengal and Tamil Nadu. Similarly, the Tamils of Sri Lanka are closer to the Sinhalese because they were always in close proximity to each other historically, linguistically, and culturally.

Gene diversity and estimation of genetic admixture among Mexican-Americans of Starr County, Texas.

The Mexican-Americans of Starr County, Texas, classified by sex and birthplace, were studied to determine the extent of genetic variation and contributions from ancestral populations such as Spanish, Amerindian and West African. Using 21 genetic marker systems, genetic distance and diversity analyses indicate that subpopulations of Mexican-Americans in Starr County are similar, and that more than 99% of the total gene diversity (HT) can be attributed to individual variation within the population. Genetic admixture analysis shows the predominant influence comes from the Spanish, a lesser contribution from Amerindians and a slight one from the West Africans. The contribution of the ancestral population to various subpopulations of the Mexican-Americans of Starr County is similar. The Mexican-Americans of Starr County are similar to the Mexican population from northeastern Mexico. The history of admixture is apparently old enough to have brought the entire Mexican-American gene pool to Hardy-Weinberg equilibrium. There is no non-random association of alleles among the genetic marker systems considered in the present study, in spite of the fact that this population is of admixed origin. These results, in aggregate, suggest genetic homogeneity of the Mexican-Americans of Starr County, Texas, and point towards the utility of this population for genetic and epidemiological studies.

Genetic structure of the populations migrating from San Luis Potosi and Zacatecas to Nuevo León in Mexico.

The Mexicans residing in the Monterrey metropolitan area in Nuevo León, Mexico, were grouped by generation and birthplace [Monterrey Metropolitan Area (MMA), San Luis Potosi (SLP), and Zacatecas (ZAC)] of the four grandparents to determine the extent of genetic variation within this population and the genetic differences, if any, between the natives living in the MMA and the immigrant populations from SLP and ZAC. Nine genetic marker systems were analyzed. The genetic distance analysis indicates that SLP and ZAC are similar to the MMA, irrespective of birthplace and generation. Gene diversity analysis (GST) suggests that more than 96% of the total gene diversity (HT) can be attributed to individual variation within the population. The genetic admixture analysis suggests that the Mexicans of the MMA, SLP, and ZAC, stratified by birthplace and generation, have received a predominantly Spanish contribution (78.5%), followed by a Mexican Indian contribution (21.5%). Similarly, admixture analysis, conducted on the population of Nuevo León and stratified by generation, indicates a substantial contribution from the MMA (64.6%), followed by ZAC (22.1%) and SLP (13.3%). Finally, we demonstrate that there is no nonrandom association of alleles among the genetic marker systems (i.e., no evidence of gametic disequilibrium) despite the Mestizo origin of this population.

Genetic diversity among the Newars of Nepal.

Genetic diversity among the Newars of Nepal has been studied using Wright's FST and the ratio of observed variance to theoretical variance following Lewontin and Krakauer's 1973 method, based on six genetic characteristics. The gene differentiation among the Newars is only 1.7%. These observations are further corroborated by the results obtained through genetic distance analysis. The average heterozygosity per locus is high (ranging from 35 to 42%) for all the groups. About 95% of total gene diversity exists within the Newar groups, the intergroup components being only about 5%.

Incidence of colourblindness in different Indian populations: further example of selection relaxation hypothesis.

Incidence of colourblindness among 1154 males belonging to seven endogamous groups viz. Brahmins, Rajputs and Shilpkars of Pithoragarh (Uttar Pradesh), Brahmins and Rajputs of Simla (Himachal Pradesh) and Kolis and Rajputs of panchmahal [Gujarat] has been reported. The frequency of colourblindness varies from 1.74% in Shilpkars to 5.0% in Kolis. Further, Indian male population data have been divided into three categories on the basis of their mode of life and habitat to test Post, Pickford and Neel and Post's hypothesis of differential selection for colourblindness.

The relationship between total ridge-count, absolute ridge-count and pattern intensity index revisited.

Although several exhaustive studies are available for qualitative finger dermatoglyphics, our knowledge on quantitative aspects of finger dermatoglyphics is far from complete. In this paper, we have tried to explore the relationship between total ridge-count (TRC) and pattern intensity index (PII), and between absolute ridge-count (ARC) and PII in 1809 Koli males--a scheduled tribe of district Panchmahals, Gujarat. It has been observed that the linear regression between ARC and PII accounts for a larger part of variation than between TRC and PII. These results further strengthen the observations made by Basu and Namboodiri and Malhotra et al. that the relationship between ARC and PII might be different in different population groups.