Genetic Markers in Human Blood

M. K. Bhasin* and H. Walter**

*Department of Anthropology, University of Delhi, Delhi 110 007, India**Eichenkamp 11, D-31789 Hameln, Germany

KEYWORDS Population Genetics. Breeding Population. Polymorphisms.Blood Groups. Serum Proteins. Red CellEnzyems. Haemoglobin Variants. HLA. DNA

ABSTRACT The human population genetics incorporates study of biology and environmental factors, as well as theforces of micro-evolution leading to macro-evolution, which ultimately influences the structure of human populations.In the present paper and attempt has been made to a give a brief review of the genetics and distribution of some of thepolymorphic traits - blood groups, human leucocyte antigens, serum proteins, red cell enzymes, haemoglobins andDNA.

INTRODUCTION

Biological Anthropology deals with thecomparative biogenetics of man. Within thevarious fields of research of the present BiologicalAnthropology the study of human evolution aswell as the study of genetic variation in modernman hold an eminent place. An important branchof Biological Anthropology is therefore Popula-tion Genetics, which deals on the one hand withexact genetic descriptions of human population,but which on the other hand tries to find out thereasons for genetic differences among them. Tostudy these genetic differentiation processes inman, which are obviously still ongoing, reliablepopulation data are necessary. As far as thevarious genetic markers of the human blood areconcerned such comprehensive reviews havebeen given e.g. by Mourant et al. (1976), Steinbergand Cook (1981), Tills et al. (1983), Roychoudhuryand Nei (1988) and Walter (1998). The existenceof genetic variation in man is caused by manyfactors, among which selection, migration andgene flow, genetic drift and founder effects arethe most important ones. By means of manyexamples, Vogel and Motulsky (1997) have shownthe importance of these factors for the under-standing of genetic variation in man. Mourantet al. (1978) have reviewed the associations bet-ween genetic markers of the blood and diseases,which are of considerable interest in thisconnection.

Recently there is an explosion of studies usingseveral DNA markers to study the geneticvariability and phylogenetic relationships of humanpopulations (Cann 2001; Basu et al. 2003; Cavalli-

Sforza and Feldmann 2003; Kivisild et al. 2003;Cordaux et al. 2004; Jorde and Wooding 2004;Reddy 2008). Now many phylogenetic trees onworld wide human populations are put forth usingthe mtDNA and Y chromosomal DNA markers tounderstand the evolution of modern human(Wallace 1995; Hammer et al. 1997, 1998; Hammerand Zegura 2002; Underhill et al. 2000, 2001;Underhill 2003; Bamshad et al. 2004; Cavalli-Sforza2005; Hunley and Long 2005; Rower et al. 2009;Alakoc et al. 2010; Grskovic et al. 2010; Serin et al.2011 among others.)

The use of polymorphic DNA segments asmarkers for diseases has greatly expanded thepotential utility and has already contributedconsiderably to our knowledge of human genomepathology (Reich et al. 2001; Collins et al. 2003;Wall and Pritchard 2003; McVean et al. 2004;Tishkoff and Kidd 2004; Takeshima et al. 2010;Anesi et al. 2012; Yang et al. 2013; Maller et al.2013; Yang et al. 2013 among others).

The unit of study is genetic variation in manis a breeding population, also referred to as aMendelian population. Following Harrison(1988) one can point out that the collective unitof evolution is the population and it is in popu-lations that all the forces we have consideredoperate (p. 326). Thus selection, gene flow,genetic drift, founder effects etc. are acting onand in populations and shape their specificgenetic profiles in the course of time. Thebreeding population is the minimal integratedunit of evolutionary changes. As far as delineat-ing evolutionary factors are concerned, thebreeding populations as a unit of study meetalmost every logical requirement unit and anychange in its genetic profile from one generationto the next will constitute an evolutionary change.

Kamla-Raj 2013 J Life Sci, 5(2): 71-121 (2013)

Address for correspondence:* Retired Professor

M. K. BHASIN AND H. WALTER

The impact of the population approach on thestudy of genetic variation in man has been to focusattention on breeding populations as biologicalor evolutionary units in man and to describe themin terms of gene frequencies or if this is not possible(anthropometric, morphological, dermatoglyphic,etc. traits) in terms of phenotype frequencies andmean values, respectively. Such exact and compre-hensive descriptions are the basic requirementsfor the understanding of genetic variation in manand thus for the analysis of the various evolu-tionary factors, which caused this variation in thecourse of time.

The populations of India and other SouthAsian countries offer great opportunities to studygenetic variability. Perhaps, nowhere in the worldpeople in a small geographic area are distributedas such a large number of ethnic, caste, religiousand linguistic groups as in India and other SouthAsian countries. All these groups are not entirelyindependent, people belong concurrently to twoor more of these groups. People of different groupsliving side by side for hundreds or even thou-sands of year try to retain their separate entitiesby practising endogamy.

The aim of the study is to have a satisfactoryknowledge of micro-evolutionary processes as theyare reflected in genetic traits in human populations.

For the present study genetic markers in humanblood are classified into the following groups:1. Blood Group Polymorphisms2. Serum Protein Polymorphisms3. Red Cell Enzyme Polymorphisms4. Haemoglobin

For more details readers are referred to theworks of the various authors (Giblett 1969; Yunis1969; Vogel and Helmbold 1972; Race and Sanger1975; Harris and Hopkinson 1976; Mourant et al.1976a, 1978; Harris 1980; Steinberg and Cook 1981;Tills et al. 1983; Mourant 1983; Livingstone 1985;Yoshida and Beutler 1986; Roychoudhury and Nei1988; Walter 1998), for blood group terminology(Lewis et al. 1990) and for guidelines for humangene nomenclature (Shows et al. 1987).

Identify and Distinguish the People

For the biogenetical study of the population,researchers have generally used the followingcriteria to identify and distinguish the people:1. Regional Groups,2. Ethnic Groups,3. Linguistic Groups, and4. Religious Groups.

It should, however, be kept in mind that theseare the convenient units of study, although thereare significant levels of overlapping betweenthem. For example, an occupational grouppursuing traditional job inhabits a region, sharesreligion with other categories, belongs to one orthe other language group and has an aggregationof ethnic properties. But in the human populationgenetic studies, out of these criteria one is chosen(Bhasin 1988).

1. Regional Groups: These can be dividedinto the following groups:a. Natural Regions: The natural regions have

broad uniformity in their characteristics, suchas relief, geomorphological history, drainage,climate, soil, natural vegetation and wild life.

b. Climatological Factors and Climatic Regions:Various climatological factors (Rainfall,Humidity, Temperature) and Altitude havebeen considered to study correlations withdifferent biological traits. A climatic regiongenerally possesses a broad uniformity inclimatic conditions produced by combinedeffects of climatic factors

c. Political Divisions: A country is comprisingof number of states, districts etc. For example,India iscomprising of 29 States and 6 UnionTerritories. In free India the distribution patternof major language groups was considered asa satisfactory basis for the formation of states.This has given a new political meaning to thegeographical patterns of the linguisticdistribution of the country.2.. Ethnic Groups: An aggregation of

biological and socio-cultural characteristicsconstitutes an ethnic group. For example in Indiawithin the category of Ethnic Group, one mayinclude Castes, Scheduled Castes, ScheduledTribes and Communities. Community generallyrefer to a group of people who may have occupa-tional, linguistic, religious or regional character-istics (Bhasin 1988).

3. Traditional Occupational Groups: In thetraditional society, there were occupational guilds.For example in India, the Chaturvarna systemwith its division into Brahman (priestly caste),Kshatriya (warrior caste), Vaishya (land ownersand traders) and Sudra (labouring caste) wasbased on occupational differentiation. Theoccupations are graded - manual labour is lookeddown upon, and those dealing with swine-herding, scavenging, butchery, removal of nightsoil are regarded as polluting (Bhasin 1988). The

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GENETIC MARKERS IN HUMAN BLOOD

caste based division of occupation is 1. Priest-hood, 2. Warfare, 3. Trade and Commerce, 4.Agriculture, 5. Animal Husbandry, 6. Artisan, and7. Menial Workers.

4. Linguistic Groups: Linguistic diversity isan important factor in the formation of regionalgroups, and it also reflects the regionaldifferentiation. There are quite good number oflanguages and innumerable dialects which changeafter few scores of kilometers. A linguistic group isan entity of social significance. There is a broadsocial integration among all the speakers of a certainlanguage. In the beginning languages and dialectsdeveloped in the different regions of the countryunder conditions of more or less isolation. Thelanguage and the dialect thus play a significantrole in defining the elements of regional identity.

1. BLOOD GROUP POLYMORPHISMS

1.1. The ABO-System

Landsteiner (1900, 1901) recognised theexistence of the ABO blood group system, inhumans comprising A, B and O groups. Decastelloand Sturli (1902) discovered the fourth group AB,of the system. In lat