Genetic Analysis of ABO and Rh Blood Groups in Backward Caste Population of Uttar Pradesh , India

A series of glycoproteins and glycolipids on red blood cell surface constitute blood group antigens. These are AB, A, B and O in ABO blood group system and Rh in rhesus blood group system. A total of 1065 unrelated Backward Caste (OBC) individuals from Uttar Pradesh were studied for the phenotype and allele frequency distribution of ABO and Rh (D) blood groups. Total 1065 samples analyzed, phenotype B blood type has the highest frequency 36.81% (n=392), followed by O (32.68%; n=348), A (23.66%; n=252) and AB (6.85%; n=73). The overall phenotypic frequencies of ABO blood groups were B>O>A>AB. The allelic frequencies of O, A, and B alleles were 0.5819, 0.1674 and 0.2506 respectively. Out of total 1065 samples, 1018 (95.59%) samples were Rh-positive and 47 (4.41%) were Rh-negative. Phenotypic frequency of Rh-negative in Koari, Yadav, Kurmi and Maurya samples were 0.99%, 4%, 1.4% and 7.6% respectively.


Introduction
The ABO blood group system is the most clinically important blood group system because antibodies against A or B or both antigens are naturally present in the serum of persons whose red cells express blood group B, A, or O.The ABO incompatible transfusions are potentially fatal.It follows that universal blood typing with DNA-based methods alone cannot be considered in the absence of a totally robust method for predicting ABO phenotype.The molecular basis of the ABO blood group system was elucidated in 1900.Landsteiner (1900) has discovered three different blood types (A, B, and O) of this ABO blood group system.The fourth blood type (AB) was discovered by DesCasterllo and Sturli (1902).The ABO antigens were originally found on red cells (Landsteiner, 1990), but later they were also found on the surface of various types of cells as well as in secretions (Davidson and Stejskal, 1962).
The ABO locus is located on chromosome 9 at 9p34.1-q34.2and encodes glycosyltransferases. ABO locus has three main allelic forms: A, B and O (Larsen et al., 1990;Hasoi, 2008;Watkins, 1980;Yamamoto et al., 1995) and Yamamoto et al. (1990) cloned and determined the structure of the gene.ABO gene spans about 18-20 kilobases (kb) organised into seven exons.Exons 6 and 7 contain 77% of the full coding region and encode the domain responsible for catalytic activity (Daniels, 2009).Exon 7 contains most of the largest coding sequence.Exon 6 contains the deletion found in most O alleles.The exons range in size from 28 to 691 bp (Yamamoto et al., 1990).The ABO gene codes for the glycosyltransferase that transfer specific sugar residues to H substance, resulting in the for-mation of group A and B antigens.A and B alleles have seven nucleotide substitutions.Four nucleotide substitutions are translated into different amino acid substitution.It has made it possible to analyze genetically ABO blood group antigens using molecular biology techniques (Larsen et al., 1990;Hasoi et al., 1998;Ogasaware et al., 1996Ogasaware et al., , 1998;;Yamamoto et al., 1990).The antigens A, B, and their variants result from functional glycosyltransferase genes capable of transferring N-acetyl-D-galactosamine or D-galactose or both to the nonreducing ends of suitable oligosaccharide chains found on red cell membrane glycoproteins and glycolipids.The red cell phenotype denoted O occurs because the glycosyltransferase gene that generates A or B or both antigens is inactive (Anstee, 2009).
The ABO blood group system was the first genetic polymorphism defined in human beings.Since that time the blood groups has played a prominent role in the study of human polymorphisms, and because of its easy classification into different phenotypes, relatively simple mode of inheritance, and different frequencies in different populations, blood groups are useful genetic markers in family, and population studies, and in linkage analysis (Ali et al., 2005).Its distribution is studied by several scientists in almost all the races and populations of the world like-Nigeria (Ahmad and Obi, 1998;Adeyemo and Soboyejo, 2006;Enosolease and Bazuaye, 2008;Gaertner et al., 1994;Jeremiaha, 2006), Kenya (Lyko et al., 1992), Palestine (Alishtayeh et al., 1988), Iraq (Mohamad, 2010), Sudan (Kalmokova and Konova, 1999;Hassan, 2010), Pakistan (Afzal et al., 1977;Ali et al., 2005;Anees and Mirza, 2005;Bhalti, 1998;Hameed et al., 2002;Khaliq et al., 1984;Khurshid et al., 1992;Khan et al., 2004;Mian and to determine the ABO and Rh blood groups frequencies in OBC population of UP.

Material and methods
Blood samples were taken by finger pricks from 1065 unrelated individuals of both sexes of OBC population, and open slide method of ABO blood groups testing was followed (Bhasin and Chahal, 1996).ABO Typing antisera of Span were used for ABO Typing.The gene frequencies for both the systems were calculated according to the method of Mourant et al. (1976).The details of each subject such as name, age, sex etc. were collected using a brief questionnaire.Informed consent was taken from each subject.Samples were collected from Koari, Yadav, Kurmi and Maurya population of Uttar Pradesh.
The Rh blood group, popularly referred to as Rhesus, is second only to the ABO system in its importance in transfusion medicine.Although the Rh system is highly polymorphic, and comprises at least 44 distinct antigens, clinically the most significant polymorphism is due to the presence or absence of the Rh (D) antigen on red cells.The Rh antigens are carried on three nonglycosylated transmembrane proteins that are encoded by two genes, RHD and RHCE (Arce et al., 1993;Avent et al., 1991;Simse et al., 1994).Alternative mRNA splicing is responsible for the production of two distinct polypeptides from the single RHCE gene.Lack of D antigen expression is usually due to the absence of the entire RHD gene from the genome of Rh (D) negative individuals (Colin et al., 1991).
Approximately 300 different types of blood groups are identified so far, indeed, the Rh and ABO antigens are still the clinically most significant (Klein and Anstee, 2005) and genetically most polymorphic of all human blood group systems to date (Blumenfeld and Patnaik, 2004).However, ABO are carbohydrate antigens (Watkins, 1966) depending on the enzymatic activity and specificity of allelic glycosyltransferases (Yamamoto et al., 1990), whereas Rh antigens are protein motifs (Gahmberg, 1982;Moore et al., 1982), whose surface expression entails an interaction of two genetic loci (Huang et al., 2000;Le et al., 2006).The protein nature endows Rh antigens, particularly the more recently evolved D antigen, with the inherent ability to mount potent alloimmune reactions to counteract such conflicting situations as fetal-maternal incompatibility (Huang and Ye, 2010).The present study was carried out  and AB blood groups were found in 207, 152, 257 and 43 individuals respectively.In female samples the phenotypic frequencies were O>B>A>AB, whereas in male samples overall phenotypic frequencies were B>O>A>AB (Tab. 2).The variation in phenotypic frequencies between male and female might be due to small sample size of male sample.

Conclusions
The frequency of ABO and Rh phenotypes in OBC appears to be similar to Asian data.The study results show that the most frequent blood group in the OBC caste group of UP is group B and the rarest is group AB and Rh-negative frequency is 4.41%.This study has a significant implication regarding the management of blood banks and transfusion services in this area.Knowledge of blood group phenotype distribution is also important for clinical studies (for example disease association), as well as for population studies.It is necessary to conduct similar well designed studies in other states of India in order to determine the blood group frequencies in them.The data generated in the present study and several other studies of different geographical region of India may be useful for health planners, while making efforts to face the future health challenges in the region.In short, generation of a simple database of blood groups, not only provides data about the availability of human blood in case of regional calamities, but also serves to enable insight into possibilities of future burden of diseases.
The frequency of ABO blood group varies from race to race.The allelic frequencies of the total population of the world is found to be O=62.3%;A=21.5% and B=16.2%.Among Western European, 42% have group A, 9% group B, 3% group AB and remaining 46% group O.American blacks generally have frequencies of A, B, AB and O blood groups of 27%, 20%, 4%, and 49% respectively (Conteras and Lubenko, 2001).Among the population of Southwest Asian countries (Saudi Arabia, Jordan, Kuwait, Syria, Iraq, Iran) the frequencies of alleles A and B are about 23 and 15 respectively (A>B), except in Afghanistan, where the allele B is higher than O and A (Ara et al., 2008;Mourant et al., 1976;Tills et al., 1983).Our frequencies are comparable with the neighboring country Afganistan and Pakistan, where the highest phenotypic frequency was of B group.
The Rh distribution also varies within any group of population.The recessive allele (d )ranges from as high as 40% to its virtual absence in Chinese Australian aborigines, Negrito etc. Exceptionally high incidence of Rh negatives yielding frequency of recessive allele (d) in the range of 50 to 60% have been reported in Basque (Europe) and Berbers of Moracco (Mourant et al., 1976).Rh -negative blood group is documented as 5.5% in south India, 5% in Nairobi, 4.5% in Nigeria, 7.3% in Lahore, 7.7% in Rawalpindi (Bhalti and Amin, 1996;Das et al., 2001;Mawuagi, 1999;Majeed and Haye, 2002).In present study, the percentage of Rh-negative was found to be 4.41% which was comparable to the earlier reports.Over the years, the Rh blood group system has been distributed among any population to keep the frequency of Rh-negative very low since clinical situations could arise through Rh incompatibility.
The need for blood group prevalence studies is multipurpose, as besides their importance in evolution; their relation to disease and environment is being increasingly sought in modern medicine.The ABO blood group has been reported to be associated with many diseases likecancer (Dabelsteen and Gao, 2005;Guleri et al., 2005;Iodice et al., 2010;Nozoe et al., 2004;Sharma et al., 2007;Vadivelu et al., 2004;Xie et al., 2010), eye diseases (Dhillon and Shergill, 2004;Khan et al., 2009;Mourant et al., 1976;Zaree et al., 2006), skin diseases (Gangopadhyay et al., 2006;Valikhani et al., 2007), cardiovascular diseases (Biswas et al., 2008;Skaik, 2009), diabetes (Koley, 2008;Okon et al., 2008), malaria (Deepa et al., 2011;Jeremiaha et al., 2010), infectious diseases like-Smallpox (Krieger and Vilente, 1969), Leprosy and cholera (Urade andChakravarty, 1999) andCholera (Harris et al., 2005) though the explanation for the association between ABO blood groups and disease is still unclear.In addition information of blood groups is very useful in blood transfusion and organ transplantation medicine, in human population migration and evolution study, in genetic research and in parental dispute cases.It is, therefore, imperative to have information on the distribution of these blood groups in any population group.The present study is therefore, useful in