Abstract
Background - Transfusion of red cells from RhD-positive donors to recipients lacking all or some epitopes of the D antigen can lead to the development of anti-D, potentially resulting in hemolytic transfusion reactions. Over 500 RHD alleles affect the qualitative or quantitative expression of the D antigen. There are huge differences in their prevalence among populations. Despite the distinct genetic diversity across multiple sub-populations in India, the prevalence of RHD alleles in the East Indian region remained unknown.
Material and methods - Standard hemagglutination tests were performed, along with molecular techniques to determine the nucleotide sequence of the RHD gene.
Results - Over 3 years, 56,445 blood donors were tested at the Tata Medical Center, Kolkata by serology. We found 23 samples with D-discrepant test results in immediate spin anti-D technique (0.04%), all of them were C+c+. Variant RHD alleles were identified in 15 samples (15/23, 65.2%). The Indian-type weak D (RHD*01W.150) was the most common variant (30.4%, No.=7), occurring in 1 in 8,063 blood donors in East India versus 1 in 729 blood donors in South India (p<0.001). Other identified variants included RHD*06.03.01 (No.=3), RHD*17.05 (No.=2), RHD*01.EL.37 (No.=2), and RHD*01W.96 (No.=1). The remaining 8 samples (8/23, 34.8%) carried the reference RHD allele (RHD*01.01).
Discussion - Our findings reveal a lower prevalence of Indian-type weak D in East India than South India, indicating region-specific genetic diversity. The high incidence of wild-type RHD allele with D-discrepancy in East India suggests a potentially novel molecular mechanism. While RHD*06.03.01 and RHD*17.05 have, the 3 others identified RHD alleles have not been associated with anti-D alloimmunization. We recommend D-negative transfusion for individuals with D-variants that have documented alloimmunization, and advocate to investigate the clinical significance of other D-variant alleles prevalent in East India, such as the Indian-type weak D.
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Authors
Suvro Sankha Datta
Department of Transfusion Medicine, Tata Medical Center, Kolkata, India
Kshitij Srivastava
Department of Transfusion Medicine, NIH Clinical Center, National Institutes of Health, Bethesda, MD, United States of America
Mercy Rophina
Council of Scientific and Industrial Research, Institute of Genomics and Integrative Biology, New Delhi, India
Vinod Scaria
Council of Scientific and Industrial Research, Institute of Genomics and Integrative Biology, New Delhi, India
Yew-Wah Liew
Red Cell Reference Laboratory, Australian Red Cross Lifeblood, Kelvin Grove, Queensland, Australia
Jenny Morrison
Red Cell Reference Laboratory, Australian Red Cross Lifeblood, Kelvin Grove, Queensland, Australia
Glenda Maree Millard
Red Cell Reference Laboratory, Australian Red Cross Lifeblood, Kelvin Grove, Queensland, Australia
Willy Albert Flegel
Department of Transfusion Medicine, NIH Clinical Center, National Institutes of Health, Bethesda, MD, United States of America
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