Molecular characterization of RhD variant phenotypes among blood donors: A study from the coastal region of India

Abstract Background Rh D expression varies with population and ethnicity. Accurate typing of Rh D antigens among blood donors is important to prevent development of anti D among recipients of blood transfusion. We aimed to screen blood donors for variant D phenotypes and accurately characterize them by genotyping. Material and methods We have done prospective study on blood donors by performing Rh D typing using three different commercial monoclonal anti-D reagents using both column agglutination and conventional tube techniques. Samples that showed ambiguous results were further screened with the Bio-Rad Partial RhD typing kit. Minor phenotyping for C, c, E, e antigens was performed. Multiplex PCR and Sequencing of all RHD exons with Sanger’s sequencing was done for molecular characterization of variant D. Results A total of 16,974 blood donors were screened during the study period. Among them, 31 (0.18%) donors were found to have a Rh D variant phenotype. The male to female ratio was 10:1. The presence of ‘C’ antigen was noted among all RhD variant samples. Serological typing showed that two samples have DV phenotypes and 29 were serologically inconclusive. Molecular genotyping characterized 90.3% of the samples as Indian specific weak D type 150 variants. Three samples were subjected to Sangers sequencing and showed wild type pattern. Conclusion The present study showed that the most common variant in this population was Weak D type 150. This study highlights that serological methods may serve as a screening tool, however, molecular techniques are essential for characterization of Rh D variants.