| Abstract|| |
Background: Diego blood group antigen, Di(a), is very rare among Caucasians and Blacks, but relatively common among the South American Indians and Asians of Mongolian origin. The antibody to Di(a) is clinically significant to cause hemolytic disease in a new-born or hemolytic transfusion reaction. Objectives: This study was designed to determine the prevalence of Di(a) antigen among the blood donors from the three major ethnic groups in Klang Valley of Malaysia as well as to find an incidence of an antibody of the Diego antigen, anti-Di(a), in a tertiary care hospital to ascertain the need to include Di(a+) red cells for an antibody screen cell panel. Materials and Methods: Serological tests were performed by column agglutination technique using commercial reagents and following instruction as per kit insert. Results: Di(a) antigen was found with a frequency of 2.1% among the Malaysians donors in three ethnic groups viz, Malay, Chinese and Indian. It was present among 1.25% of 401 Malay, 4.01% of Chinese and 0.88% of 114 Indian origin donors. None of the 1442 patients, including 703 antenatal outpatients, had anti-Di(a) in serum. Conclusion: The prevalence of Di(a) antigen was found among the donors of all the three ethnic background with varying frequency. Inclusion of Di(a+) red cells in routine antibody screening program would certainly help in detection of this clinically significant antibody and to provide safe blood transfusion in the Klang Valley, though the incidence of antibody appears to be very low in the region.
Keywords: Anti-Di(a), Di(a), Klang Valley, Malaysia, prevalence
|How to cite this article:|
Wei CT, Al-Hassan FM, Naim N, Knight A, Joshi SR. Prevalence of Diego blood group antigen and the antibody in three ethnic population groups in Klang valley of Malaysia. Asian J Transfus Sci 2013;7:26-8
|How to cite this URL:|
Wei CT, Al-Hassan FM, Naim N, Knight A, Joshi SR. Prevalence of Diego blood group antigen and the antibody in three ethnic population groups in Klang valley of Malaysia. Asian J Transfus Sci [serial online] 2013 [cited 2018 Nov 15];7:26-8. Available from: http://www.ajts.org/text.asp?2013/7/1/26/106725
| Introduction|| |
An antibody of the Diego antigen, Anti-Di(a), was first described by Layrisse et al.  as the cause of HDN in the serum of a Venezuelan woman. Antithetical antibody, designated as anti-Di(b) was reported a decade later by Thompson et al.  and a new blood group system was evolved. The system was further expanded through its genetic association with already existing antithetical pair of Wr(a)/ Wr(b).  The Diego blood group system, in its present form, consists of two closely linked pairs of Di(a)/ Di(b) and Wr(a)/ Wr(b) of which the Di(b) and Wr(b) are the high frequency antigens whereas the Di(a) and Wr(a) occur as the low frequency antigens. 
Although the Di(a) antigen is found with a very low frequency (<0.01%) among the Caucasians and Blacks,  its incidence among the Native American Indians and Asians with Mongoloid extraction is not that rare. The prevalence of Di(a) antigen in South American Indians was reported as high as 36%, and in Asians of Mongoloid origin like Japanese, Chinese and Koreans have its prevalence any way between 5 and 15%. ,, The high prevalence of Di(a) antigen in Asian populations with Mongolian ancestry makes it interesting to both, those working with the anthropology as well as the transfusion medicine.
Anti-Di(a) was occasionally incriminated as a cause of hemolytic transfusion reactions and hemolytic disease of the newborn. ,,, Although the prevalence of Di(a) antigen among the Asians of Mongoloid ancestry has been worked out well, none of the study address its incidence in Malaysian population comprising three ethnic groups viz., Malay, Chinese and Indian. Likewise, there is no report available on an occurrence of clinically significant anti-Di(a) antibody in Malaysians of diverse ethnicity.
| Materials and Methods|| |
The blood samples for detection of the Di(a) antigen were obtained from healthy volunteer blood donors through blood donation drives, organized by the National Blood Transfusion Centre, Kuala Lumpur. Ethical approval was granted by research and Ethics committee and informed consent was obtained from all the blood donors participated in this study. A total of 1170 blood donors' samples were collected from 29/11/2008 to 20/01/2009.
The blood samples to screen for anti-Di(a) antibody were obtained during the study period between 21/11/2008 and 20/01/2009 on the patients (n = 759) admitted as inpatients to, as well as the pregnant women (n = 716) attending antenatal clinic at Kuala Lumpur Hospital (HKL) in the city of Kuala Lumpur.
The test for Di(a) antigen on red cells was performed using commercial anti-Di(a) (Immucor Gamma, USA) and the LISS/Coombs card (DiaMed AG) as per the instruction insert in the kits. The known Di(a+) and Di(a-) cells used as controls/for the antibody screening test were made available commercially from the Commonwealth Serum Laboratories, Australia. Direct Antiglobulin Test (DAT) was performed for all donor samples that gave positive results to rule out false positive results, if any. The test for anti-Di(a) was also carried out using Di(a+) red cells using the LISS/Coombs card (DiaMed AG).
The Chi-square test on the data obtained was carried out using SPSS 12.0, the Window software program to find an association between the ethnicity and the prevalence of the Di(a) antigen.
| Results|| |
[Table 1] shows distribution of the Di(a) antigen among 1089 Malaysian blood donors in three ethnic groups. The Di(a) antigen was present in 23 of the 574 Chinese, 5 out of 401 Malays, and 1 out of 114 Indians, thereby showing the incidence of Di(a+) phenotype as 4.01%, 1.25% and 0.88%, respectively, with a significant intergroup difference (P = 0.014, < 0.05) in distribution of the antigen among the three groups. This observation has also indicated that each of the groups were maintaining its ethnic identity through endogamous social structure of one's own.
|Table 1: Prevalence and association of Di(a) antigen for different ethnic groups living in Klang Valley, Malaysia|
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Antibody screening using known Di(a+) red cells was carried out on the 739 inpatients including 510 Malays, 111 Chinese, 118 Indians, as well as 703 patients attending antenatal clinic that included 554 Malays, 81 Chinese, 68 Indians. None of these 1442 patients were tested positive for anti-Di(a) antibody. The data is not tabulated.
| Discussion|| |
The Di(a) antigen is very rare among Caucasians and Blacks, but is relatively common among South American Indians and Asian population, especially in people of Mongolian origin.  The Diego blood group system, therefore interest more to the anthropologists than to the hematologists, However, the differential prevalence of Di(a) antigen is also important in the field of transfusion medicine as Di(a) incompatibility may give rise to alloimmunization that cause HTR , and HDN. ,
The major ethnic groups living in Klang Valley, Malaysia is comprised of those having their origin in the Malays, the Chinese and the Indians. In earlier study,  Di(a+) phenotype was found in one among the 71 Malay blood donors tested from Penang state of Malaysia which yield an incidence of 1.43%. The present study substantiated the earlier observation by studying a larger sample size in which the five out of 401 Malay donors (1.25%) tested positive for Di(a) antigen. However, we noticed a significant difference (P = 0.014) for prevalence of the Di(a) antigen among the Malays, Chinese and Indians ethnic groups in Klang Valley. Interestingly, we found prevalence of Di(a+) phenotype as (4.01%), in the Malaysian Chinese is similar to the Chinese from Taiwan (3.2%) and Hong Kong (4.4%) situated in the south of the main land China.  On the other hand, the Chinese from the north region have a higher incidence (10.3%) of Di(a+) phenotype  as was found in different neighboring countries like Japan having 10% Di(a+),  Korea with 6.4-14.5% and Mongolia with 7-13%. , Therefore, it is as conceivable that the Japanese and Koreans have their descendence in Northern China or Mongolia as Chinese settled in Klang Valley have their origin in the southern part of China. ,
In this study, the Malaysians of Indian origin showed 0.88% prevalence of Di(a+) phenotype which is quite lower than that of 4% from the North Indian population.  This difference could be due to the fact that the Malaysian Indians have their descendents come from Tamil-speaking Southern India that have genetic diversity from the North Indian population. Besides, the Northern and the Northeast regions of India bear geographical proximity with bordering Nepal, Tibet and China so it is not surprising to find a higher incidence of Di(a+) phenotype in the Northern region of India. However, there is no study reported on Di(a+) phenotype status among the Tamil-speaking population of Southern India to compare the same in Malaysian Indians.
The overall prevalence of Di(a+) phenotype as 2.1% in Klang Valley may have clinical impact in terms of all immunization through blood transfusion or pregnancy that may eventually result in mild to as severe as fatal blood transfusion reaction. , In Japan, after the reported incidence of hemolytic transfusion reaction,  the country has adopted to screen for the anti-Di(a) antibody in routine for all blood transfusion recipients. Likewise, anti-Di(a) antibody has also been implicated as clinically significant to cause the hemolytic disease of the newborn. ,
In present study, none of the samples tested was found as positive for anti-Di(a) antibody among the 1475 patients tested in the region, even though the prevalence of Di(a) antigen was found as 2.1%. Han et al.  have reported an incidence of anti-Di(a) as 8 out of 11,219 (0.07%) in face of a prevalence of the Di(a) antigen to be as high as 6.4-14.5% in Korea. Besides, seven of these eight cases had history of blood transfusions or multiple pregnancies as well and that could be a contributory factor for a higher incidence, , as the history of transfusions has greater impact in occurrence of anti-Di(a). In the present study, the sample size of the patients tested for the antibody vis-à-vis incidence of Di(a+) cases studied in Klang Valley is lower than the other reported series hence one can expect a lower incidence of anti-Di(a) antibody. However, it is important to include the Di(a+) red cells as screen cells to detect the clinically significant anti-Di(a) in countries like Malaysia and other Southeast and East-Asian countries where the Di(a) antigen is prevalent.
| Conclusions|| |
The Di(a) antigen in Malaysians of different ethnic background has variable prevalence of the Di(a) antigen is, the Chinese having the highest and the Indians with the lowest. It is advisable to screen the transfusion recipients for anti-Di(a) in the region inhabited by the Chinese population, though none of the patients in our series had shown a presence of anti-Di(a) presumably due to a lower sample size for such study and that too among the patients with little history of transfusion.
| Acknowledgments|| |
We are very grateful to the Universiti Sains Malaysia (USM) for funding this study. We would also like to express our sincere thanks to the director of the National Blood Centre, Kuala Lumpur for the commitment and help rendered throughout.
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Faisal Muti Al-Hassan
Cluster of Regenerative Medicine, Advanced Medical and Dental Institute, Universiti Sains Malaysia, No: 6, Tingkat 1, Lot 13, Persiaran Seksyen 4/9, Bandar Putra Bertam, 13200 Kepala Batas, Penang
Source of Support: The present study was supported through grant provided by the Universiti Sains Malaysia and there was no conflict of interest tagged in any form., Conflict of Interest: None