A Genetic Study Among the Padam of Bolung Village, lower Dibang Valley District Arunachal Pradesh

Abstract

This paper describes the genetic characteristics among the Padam of Bolung village in Arunachal Pradesh, which was carried out with the help of four genetic markers namely, ABO blood groups, Rh(D) blood groups, Phenylthiocarbamide (PTC) taste sensitivity, and colour blindness. A total of 215 individuals were tested out of which 106 were males and 109 were females. Method suggested by Lawler and Lawler (1951) and Bhatia (1977) was followed to collect data on ABO and Rh blood group. For PTC taste sensitivity Serial dilution method suggested by Harris and Kalmus (1949) was followed to collect data. Ishihara Chart (1959) method was used to collect data on Colour blindness. It was found that the present population is in genetic equilibrium with respect to the ABO blood group system. Out of215 individuals tested, percentage distribution of Rh negative individuals is zero. The frequency of colour blindness in the population is 9.43%, that is, out of 106 individuals 10 males were detected as having red green deficiency. About 12.04% of the total individuals covered under the study were non-tasters. Allele frequencies for Taster and Non-taster are 0.652 ± 0.0316 and 0.3480 ± 0.0316 respectively. However, when compared with other populations, the Padam population seems to be genetically distinct, i.e., it is statistically different from other populations of Arunachal Pradesh in respect of the distribution of the ABO blood groups. On the other hand, other genetic markers like PTC taste sensitivity and colour blindness indicated that the Padam population is similar to other populations of Northeast India. It may, however, be noted that genetic markers like PTC taste sensitivity and colour blindness are considered as weak genetic markers in comparison with the ABO blood groups system. INTRODUCTION Traditionally, physical anthropology is primarily concerned with the taxonomic classification of human population at both micro and macro levels with a view to understanding the processes of human evolution in space and time. Indeed, ascertaining *Address for Communication: Department of Anthropology, North Eastern Hills University, Shillong. The Oriental Anthropologist, Vol. 18, No. 2, 2018, Pages 319-331 © OICSR, Allahabad Corresponding Author E-mail :rrimonbasuk@gmail.com 320 Rimonbasukshisha Radborne this history has always been and remains one of the main goals of physical anthropology (Harrison, 1977). Accordingly, it has been felt necessary to use discrete characters or genetic markers like blood groups, red cell enzymes, serum proteins, etc., for understanding the evolutionary processes of human populations. According to Li (1955), Population genetics is concerned with the statistical consequences of Mendelism in a group of families, or individuals, it studies the hereditary phenomenon on population level. It is well acknowledged that each population consists of individuals with a different genotype, or genetic constitution. The number of individuals with a particular genetic trait that is controlled by a pair of alleles at a given locus in a chromosome can be counted and thereby the frequency of such a gene can be calculated in a population. The 'array of gene frequencies over all loci' in a population is known as gene pool, or genetic constitution. If the gene frequencies in a population remain unchanged from generation to generation, such a population is said to be in genetic equilibrium. According to HardyWeinberg law, the genetic equilibrium is supposed to take place when the population is large and the mating is at random along with the absence of other evolutionary forces like selection. Population genetics is also very useful in the field of medical sciences. For example, it is commonly cited that the frequency of the sickle cell trait in Africa is higher in the agricultural communities than in those communities, which depend largely on hunting or animal husbandry. It has been observed that the clearing of forests for cultivation has created the new breeding areas for the mosquitoes (Anopheles gambae), the vectors of malaria parasite (Plasmodium falciparum) . As a result, there is a wide spread of malaria in those populations, which depend on agriculture. The question is that how these populations are maintaining themselves? It is found that the spread of malaria due to agricultural practices in these populations is responsible for the selective advantage of the heterozygote for the sickling gene, i.e. the heterozygous individuals (HbAHbS) are more resistant to malarial parasites than the normal homozygotes (HbAHbA) and homozygous affected individuals (HbSHbS) . Accordingly, the frequency of the sickle cell trait is very high in these populations of malaria prone areas. So although the sickle cell gene is harmful, if it is expressed in homozygous condition, it is also beneficial to the carriers of the trait (heterozygotes) since they have better resistance to malarial parasites. Another important fit:!ld of population genetic research is concerned with the genetic and health aspect bf inbreeding. According to Reid (1973), Inbreeding is the genetic consequences of biologically consanguineous mating, ahd the offspring of biologiCally consanguineous mating are said to be inbred. The Oriental Anthropologist A Genetic Study Among the Padam of Bolung Village, 321 lower Dibang Valley District Arunachal Pradesh OBJECTIVES OF THE PRESENT STUDY In the present study, we propose to undertake a genetic study analysis the Padam tribe of Arunachal Pradesh taking into consideration the following objectives of study: 1. To describe the genetic composition of the Padam population with the help of some genetic markers like ABO and Rh (D) blood groups, PTC taste blindness and colour blindness. 2. To understand the phylogenetic position of the study population in relation to other neighbouring populations of Arunachal Pradesh and other populations of Northeast India. MATERIALS AND METHODS Blood samples on 215 individuals of which 106 males and 109 females were collected from Bolung village of Lower Dibang valley district of Arunachal Pradesh. The standard slide method suggested by Lawler and Lawler (1951) and Bhatia (1977) was followed for collection of blood samples in the present study. For PTC taste sensitivity Serial dilution method suggested by Harris and Kalmus (1949) was followed to collect data. Ishihara Chart (1959) method was used to collect data on Colour blindness. In the present study, the differences between populations in respect of the percentage frequencies of genetic markers like ABO blood groups and PTC taste sensitivity were tested by using the chi-square (X2). RESULTS ABO Blood Groups The phenotype and allele frequencies of ABO blood groups from a total sample of 215 individuals106 males and 109 females are given in Table 1. It is seen from the table that the percentage frequencies of 0, A, B and AB in males are 18.87%, 34.91%, 35.85% and 10.38% respectively. In the case of females, these frequencies are 26.61%, 23.85%, 35.78% and 13.76%, respectively. These sex differences in respect of the phenotype distribution of the ABO blood groups are statistically significant (X = 4.17, DF = 1, P>0.05). However, since ABO locus is an autosomal character, data on both males and females were pooled together to find out the allele frequencies of the ABO blood groups. Thus, combining the data on both sexes the percentage frequencies of A, B, AB and 0 are 29.30%, 35.81%, 12.04% and 22.79% respectively. Following the methods given by Bernstein (1931) and Balakrishnan (1985), the gene frequencies of p, q and rare 0.2319 ± 0.022, 0.2886± 0.024 and 0.4795± 0.027, respectively. Applying the test of goodness of fit, it is found population are not statistically significant (X2 =0.4949, DF=1, P>0.05). The Oriental Anthropologist 322 Rimonbasukshisha Radborne Thus it indicates that the present population is in genetic equilibrium from the genetic point of view. A population is said to be in genetic equilibrium when the gene frequencies do not deviate significantly from the prediction of Hardy Weinberg law, which states that the gene frequencies remain constant from generation to generation. Table 1 Phenotype and allele frequencies of ABO blood groups MALE(n=106) PHENOTYPE NUMBER 0 20 A 37 B 38 AB 11 Allele frequencies ± Standard Error (SE) p q 0.2319 ± 0.022 0.2886 ± 0.024 0.4795 ± 0.027 %