Objective: To determine frequency of ABO and Rhesus blood groups in our population and to compare it with reports of various countries.
Material and Methods: The study included blood donor- and recipient records of 12 years (1988 to 2000) of the Blood Transfusion and Immunohaematology Department of the 710 bedded SMHS Hospital, the biggest general hospital of the JandK State. A total of 1,00,980 population was screened. ABO and Rhesus blood groups were determined by standard methods.
Results: 'O' was the most prevalent blood group ie, 38.43%, while AB was the least prevalent group ie, 6.55%. Majority 95.9% were Rhesus positive. Data showed that among the Rh +ve, 36.47% were O +ve, 30.91% B +ve, 22.16% A +ve and 6.35% AB +ve. Break up of the Rh -ve, 1.95% were O -ve, 1.14% B -ve, A- 0.79% A-ve, and 0.2% AB -ve.
Conclusion: Blood group 'O' is the commonest blood group in our community, followed by B, A and AB respectively. More than 95% of our population is Rhesus positive.
Key Words: Blood group, ABO, Rhesus, Frequency, Kashmir.
The ABO and Rhesus blood groups were discovered and identified in 1900 and 1940 respectively. The ABO blood group system is the only system in which antibodies are consistently and predictably present in the serum of normal individuals whose red cells lack the antigens. The ABO system remains by far the most significant for transfusion.
The ABO system includes many phenotypes and several antibody specificities. The second type of blood group is the Rhesus system. There are only two Rhesus phenotypes ie rhesus positive and rhesus negative, depending on whether Rh antigen is present on the red cells or not. The D antigen, after A and B, is the most important red cell antigen in transfusion practice. Unlike the situation with A and B, persons whose red cells lack the D antigen do not regularly have anti-D in their serum. Formation of antibody almost always results from exposure, through either transfusion or pregnancy, to the immunizing red cells possessing the D antigen.
Interestingly, both ABO and Rhesus blood groups exhibit extensive polymorphism in different populations and the frequency at which each of the blood groups exists shows considerable variations in different populations. The current study was carried out with the specific aim of determining the frequency of ABO and Rhesus phenotypes in the Kashmiri population and to compare the results with distribution among other populations.
The study group included a total of 1,00,980 subjects, ie 64,024 donors (Males 62,962, Females 1,062) and 36,956 recipients (Males 26,665, Females 10,291). The blood samples were obtained by standard procedures of venepuncture after filling all the essential information regarding donors and recipients, and subjected to determination of ABO and Rhesus blood groups by combined slide and tube method using standard antisera. The records were scrutinised only for native population; non-Kashmiris were excluded. All donations were voluntary (in blood donation camps) or replacement (hospitals) made in rural and urban areas over a period of 12 years. Each sample of donors and recipients was labelled and recorded according to its ABO phenotype and rhesus status. Results were compared with similar group prevalence studies from India and abroad.
The prevalence of phenotypes A, B, AB and O was estimated in both donors and recipients. Results are presented in Table 1. The commonest blood group in Kashmiri population was blood group O, followed, in order, by B, A and AB. Respective prevalence of Rhesus positive and negative phenotype is presented in Table 1. More than 95% of our population turned out to be Rhesus positive. The prevalence of the ABO phenotypes vis-a-vis the Rhesus phenotype was O+ (36.47%), followed by B+ (30.91%), A+ (22.16%), AB+ (6.35%). The lowest prevalence was that of AB- ie, 0.2% (Table II).
Our study has determined the distribution frequency of ABO and Rhesus blood groups in Kashmiri donors and recipients. Populations across the globe differ in the distribution of blood group phenotypes. Frequency of blood group O is higher in our population; other populations in our country2-4 and other countries (Algeria, Egypt, Saudi Arabia, Bangladesh, Libya, Italy, Kuwait, Iran, England, Greece) also show similar trends (Table III). Blood group B was the second commonest blood group after O in our community. Similar frequencies are reported in different Indian studies and from Bangladesh. Blood group A followed B in our State. This is in sharp contrast to the situation in Germany, Lebanon, Turkey, France, and Hungary, where A group is the most prevalent group and exceeds B, O, AB, in that order. Again, A is the 2nd most common blood group after O in Algeria, Egypt, Saudi Arabia, Bangladesh, Libya, Italy, Kuwait, Iran, England and Greece. The blood group studies from all these populations group the males and females together. This is because blood groups are autosomal, thus the frequencies are not different in the two sexes. Merely 5% of our population was Rhesus negative compared to 17% in the UK. It suggests that the expected frequency of Rhesus iso-immunization would be lower in Kashmir than that encountered in the UK population. Prior to the availability of anti-IgG immunoglobulin only a few studies are available for comparison in Kashmir. One (unpublished) report on 'Incidence of blood groups in Kashmir' conducted in 1974 on 9315 subjects, revealed that group B was the most commonly encountered group (37.5%), followed by O (35.5%), A (21.3%) and AB (5.9%). Frequency of Rhesus negative subjects was 12.69%. It suggests that blood group 'O' has increased from 35.3 to 38.43, A from 21.3% to 22.95%, while as AB has increased from 5.9% to 6.55%, while blood group B has decreased from 37.5% to 32.05%. During the same period, significant fall occurred in the Rh -ve group from 12.69% to 4.09%. These differences may possibly have been due to a real shift in genetic frequencies caused by a dramatic rural to urban migration to Srinagar - the summer capital of JandK State, with better opportunities for education, and employment. Differences may have been attributable to a significant improvement in blood group determination technology. However, the smaller size of the study population in the earlier (1974) study could have been responsible for the difference in results.
|Donors = 64024; (M=62962/ F = 1062).|
|Recipients = 36956; (M= 26665/ F=10291)|
Note: A study from Pakistan22 on 201 subjects showed higher frequency of blood group B=76 (37.81%), followed by O= 68 (33.83%), A= 43 (21.39%), and AB= 14 (6.97%)
Our study could have several significant implications. Firstly, it provides information to various blood banks of the State regarding the higher need of blood group O for transfusion purposes - particularly the surgical patients, since more than 50% transfusions are required for routine surgeries and surgical emergencies. Secondly, it could have significant public health implications for our population; studies linking ABO blood groups to cardiovascular diseases have confirmed a lower relative frequency of group O in persons affected by coronary heart disease, ischemic heart disease, venous thrombo-embolism, atherosclerosis, etc. Studies have also suggested a higher in vitro heparin anticoagulant effect in the group O individuals.23-28
Several studies have reported an association between blood groups and certain disease states29,30 and it is possible that higher frequency of blood group O has a protective effect against some diseases in Kashmiri people.
Thirdly, this study shows variations in the frequency of blood groups over time due either to genetic or technical reasons. If we consider that blood groups in Kashmir over the last decades have changed due to population movement to the capital city, then we may be suggesting that blood group frequencies may be different in different areas of Kashmir. Thinking in that direction may not completely be irrelevant since Kashmiris are essentially comprised of different racial groups who included migrants or invaders from Israel, Central Asia, Mongolia, Persia, Tibet, Afghanistan, etc. Thus it is necessary to conduct similar studies in different parts of Kashmir in order to determine the blood group frequencies in different regions.
Dr Javed Ahmad Latoo,
44 Cantley Gardens, Gants Hill,
Ilford (London) IG2 6QB, United Kingdom