Background: Molecular bases of blood group systems, including Rh blood group, have been poorly studied in the Indian population so far, while specificities of Europeans, East Asians and Africans have been well known for years. In order to gain insights into the molecular bases of this population, we sought to characterize the RHD allele in D- Indian donors expressing C and/or E antigen(s). Methods:RHD gene was analyzed in 171 serologically D-, C/E+ samples by standard molecular methods such as quantitative, multiplex PCR of short fluorescent fragments (QMPSF) and direct sequencing when necessary. Results:RHD whole gene deletion at the homozygous state was found to be the most common genotype associated with D- phenotype (118/171, 69.0%). Nonfunctional, negative hybrid genes with reported molecular backgrounds were observed in approximately one-third of the samples, while only four samples carry single-nucleotide variations, including one novel nonsense (RHD(Y243X)), one novel frameshift (RHD(c.701delG)), and two missense (RHD(T148R) and RHD(T148R, T195M)) alleles. Conclusion: Overall we report for the first time the molecular bases of D antigen negativity in the D-, C/E+ Indian population, which appears to be qualitatively similar to other populations, but with a population-specific, quantitative distribution of D-- alleles.
Background
D antigen is one among the most immunogenic antigens and is the most common cause of Haemolytic Disease of Fetus and Newborn (HDFN). The D‐phenotype is a rare Rh variant in which none of the RhCE antigens are expressed on the red cell surface. Individuals having D‐phenotype are capable of producing a rare alloantibody named as anti‐Rh17(Hr°) in response to pregnancy or transfusion and has the potential to react with C/c and E/e antigens causing severe haemolytic transfusion reaction (HTR) and haemolytic disease of fetus and newborn (HDFN).
Case report
We have encountered a case of severe HDFN with an accidental discovery of D‐ phenotype of the mother with anti‐Rh‐17 antibodies. D‐ phenotype has been confirmed with molecular typing along with genotyping of all family members.
Conclusion
Rare phenotypes like D‐ individuals especially if allo‐immunised are of great concern at times of transfusion requirements. Hence, proper identification of these individuals are important to contribute them to the rare donor pool and to adopt adequate patient blood management strategies.
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