Nepal is an ethnically rich country which involves variations in language, religion, caste system among different groups. In addition, it has been observed that for the last few decades there is considerable migration by peoples within the country leading to a far greater demographic mixing of groups than in the past.
The purpose of this study is to reveal trend of blood group distribution (ABO and Rh) in the population of Pokhara valley. The study is both prospective and retrospective and included data both from community and patients coming to MTH in the period from January 2007 to December 2009. The frequency of distribution was 26.77% of A, 29.38% of B, 8.84% of AB, 35% of O. Only 3.22% of them were found to be Rh (-) ve.
From this study it has been seen that in Brahmin, & Chhetri population, there is a dominance of O blood group but in Baishya, A group is predominant. In Sudra A blood group is comparatively less than others; B & O blood group peoples are maximum in that population.
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Keywords: A B O blood group, Rh type.
Scientist Landsteiner first described the ABO blood group in 1900 and it served the beginning of blood banking and transfusion medicine1. Blood grouping is based on antigenic property of red blood cells (RBC). It is one of the important tools for anthropological study of ethnic origin of people and to avoid hazards of mismatched blood transfusion. The gene for ABO group is present on chromosome 9 while for Rh system it is on chromosome 1.The Rh system is one of the most polymorphic of the human blood groups.
The RBC membrane contains different types of blood group antigens and the most important are A and B antigens. These antigens are complex oligosaccharides which differ in their terminal sugars. The antibodies against red cell antigens which are acquired during early childhood are called agglutinins and are found in plasma. According to the presence of these antigens and antibodies blood is divided into four major groups called A, B, AB and O. Group A blood has type A antigens, group B blood has type B antigens , group AB has both and group O blood has none. Also plasma from blood group A contains Anti-B antibodies which act against type B antigens, whereas plasma from type B blood contains Anti-A antibodies, which act against type A antigens. Type AB has neither type of antibody and type O blood has both Anti-A and Anti-B antibodies2.
Human red blood cell contains another important antigen called antigen D. According to the presence or absence of Rh antigens, blood is classified into Rh positive or negative.
The distribution of ABO and Rh blood group varies from race to race. Report indicates that, among the Nepalese medical students the frequency of A, B, AB and O blood group was found to be 29.0%, 26.0%, 13.0% and 32.0% respectively3. The study of blood grouping is very important as it plays a crucial role in genetics, blood transfusion, forensic pathology and may have some association with diseases like duodenal ulcer, diabetes mellitus, urinary tract infection, feto-maternal incompatibility leading to hemolytic diseases of newborn4-6,. Emergency situations demanding blood donations and transfusion is also common now a day. Nevertheless, the number of subjects screened was rather less. So, present study was undertaken to observe the frequency of blood groups among 2297 Nepalese people from both community and the patients who attended Manipal Teaching Hospital, Pokhara during the period from January 2007 to December 2009.
MATERIALS AND METHODS
It was a hospital based observational study carried out in the data retrieved from the register maintained in the blood bank of department of pathology of the Manipal Teaching Hospital, Pokhara, Nepal in 2010. The variables collected were Sex, ethnicity, ABO and Rh blood group. Conventional glass slide method was used. Blood samples were collected by finger prick with a sterile lancet, after cleaning the puncture site with 70% ethyl alcohol. A drop of monoclonal anti-sera, anti A and anti B (manufacturer : Tulip Diagnostics , India ) was placed on glass slides. Then a drop of finger prick blood added on slides respectively and mixed well. Results of agglutination were recorded after 4 minutes. Similarly tests were carried out with anti D anti-sera. Agglutination was checked under microscope and if present indicated positive result.
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The data was analyzed using Excel 2003, R 2.8.0 Statistical Package for the Social Sciences (SPSS) for Windows Version 16.0 (SPSS Inc; Chicago, IL, USA) and the EPI Info 3.5.1 Windows Version. The chi-square test was used to examine the association between different variables. A p-value of < 0.05 (two-tailed) was used to establish statistical significance.
Out of 2297 subjects, the distribution of ABO blood groups in both Rh (D) positive and negative subjects are illustrated in Table 1 and it is having a statistical relationship ( p=0.0001 ). The frequency of distribution of A, B, AB and O was found to be 26.77%, 29.38%, 8.84%, 35% respectively. There is a dominancy seen in O blood group (35%), while the AB blood group was the lowest (8.84%). Considering Rh group together, the overall commonest blood group was O (+) and the least common was AB(-) followed by O (-). Majority of the population having Rh (+) blood group and only 3.22% of total subjects were found to have Rh (-) ve blood.
Table 2 and Table 3 encompasses caste wise distribution ( both numbers and percentages ) of all the blood groups with a statistical association (p=0.0001). Analyzing data's of Table 2 and Table 3, it is clear that in Brahmin, & Chhetri population, there is a dominance of O blood group but in Baishya, A group is predominant. The second most prevalent blood group in Brahmins, Chhetri and Baishya are B, A and B respectively. In Sudra the two commonest groups are O and B respectively.
The ethnic situation in Nepal involves variations in language, caste status, ethnicity, religion, and region among different groups. The Hindu caste system organizes village life in central and southern Nepal. The two most significant groups of Indian origin in Nepal, both in the central region and across the nation, are the Brahmins and Chhetris. Except these the others are Baishya & Sudra. The need for blood group prevalence studies in Pokhara is not only important for blood transfusion, organ transplantation and genetic research, but also in evolution that helps scientists to understand the place humans occupying evolution's branching tree7. It has been found in American population that the frequency of O, A, B and AB blood group is 45.0%, 41.0%, 10.0% and 4.0% respectively8. From medical reports it has been seen that, Asian Mongoloids has higher frequency of A gene and relatively low B is observed in population of Korea, Japan, several Asiatic population of USSR and North East part of India.9,10 Recent research showed that, among the Jirels of Nepal, a small tribe who are the descendents of Kirat tribe (Mongoloids) A group is predominant.11 From this study, it is clear that in Brahmin, & Chhetri population, there is a dominance of O blood group but in Baishya, A group is predominant. In Sudra A blood group is comparatively less than others, B & O blood group peoples are maximum in that population. Rh factor is positive in all the four blood group people, and very less prevalence of Rh negativity (3.22%). Persons having blood group O poses a risk factor for duodenal ulcer 12. Blood group B has highest frequency of Diabetes Type II 13. But Coronary artery disease (CAD) risk is same in all blood groups.14 .
A similar distribution of ABO blood groups to our study was found in Kathmandu vally22.
Countries such as Syrian Arabs, Lebanon, Israel, Jordan and Tehran have a different ABO spectrum in which blood group-A is the predominant16 - 20. Rh (D) positive individuals reported the highest percentage in this study and this is in agreement with previous studies that Asians have mostly (99.0%) Rh (+) ve21.
The present study is having an importance because; it's the first comprehensive study on blood group done in Pokhara Valley. Blood group distribution study helping researchers to find out proper reasons of increasing of one blood group to another by linked genetic influences and also role of inter and intra marital system in the society.