BACKGROUND India is a vast country with several population groups. But minimum data is available about the frequency of different Rh blood group antigens among the Indian population, whereas no data has been reported from Kerala till date. The antigen frequency in a specific population may help us to assess the risk of antibody formation and which in turn may give direction to get an antigen-negative compatible blood for patients who have multiple red cell alloantibodies. This study was carried out to determine the frequencies of Rh blood group antigens D, C, c, E and e among 500 blood donors. MATERIALS AND METHODS This is a descriptive study done on 500 blood donors who came to the Department of Transfusion Medicine, Govt. T. D. Medical College, Alappuzha. Samples from randomly selected blood donors of nearby areas (both voluntary and replacement) were collected for extended Rh antigen phenotyping during the one-year period of study (February 2015 to January 2016). RESULTS Among the 500 blood donors included in the study, 470 (94%) were males and 30 (6%) were females. 86.6% (n= 433) of the donors were found to be Rh D positive and the remaining 13.4% (n= 67) were Rh D negative. Most common Rh antigen observed in the study population was e (96.8%) followed by D (86.6%), C (80.8%), c (61%) and at last E (12.4%). Out of 433 Rh D positive randomly selected blood donors in the study, the most common phenotype was found to be R1R1 (39%) followed by R(1)r (34.6%). Among 67 Rh D negative subjects, r r was the commonest phenotype (60 out of 67). CONCLUSION This study emphasises the need for implementing Rh-phenotyping on routine blood grouping to provide antigen negative compatible blood when in demand. Rh antigenic phenotyping along with antibody identification is crucial, especially in transfusion dependent and multiparous females. It is a vital requirement of a quality transfusion service. From the different reaction patterns observed in this study, the prevalence of probable Rh phenotypes were assessed and it helped to create an antigen negative donor database.
