Frequency Distribution of ABO Blood Group and Rh Factor among the Third Gender in Bangladesh

Introduction: The ABO and Rhesus (Rh) blood group systems are the most clinically important blood group classifications and play a fundamental role in transfusion medicine, organ transplantation, population genetics, and disease association studies. Although the distribution of ABO and Rh blood groups has been extensively investigated in different populations, no study has reported their distribution among the third gender community in Bangladesh.Aims: Distribution of blood groups is an essential consideration in transfusion medicine, which varies across populations, regions and ethnic groups. The frequency of Blood group have investigated by several study but none have focused on the third gender community in Bangladesh. This study aims to determine the distribution of ABO and Rh blood groups among the third gender in Sylhet, Bangladesh. Methodology: A total of 161 third gender given blood samples voluntarily. Blood grouping was evaluated by the slide agglutination method with Anti-A, anti-B, and Anti-D sera. The entire study was conducted under the Department of Surgery and Theriogenology, Sylhet Agricultural University, Sylhet, Bangladesh.Results: Blood group O was most frequent (40.4%), followed by B (29.8%), A (24.2%) and AB (5.6%). Rh positive was more frequent (96.3%) compared to Rh negative (3.7%) blood. Additionally, in the case of blood group and Rh factor combination, this study found an order of O (+ve) > B (+ve) > A (+ve) > AB (+ve) > O (-ve) = B (-ve) = A (-ve) > AB (-ve). As no previous study on blood group distribution among the third gender population in Bangladesh was available for comparison, the present findings were assessed alongside existing data from cisgender populations. Although slight regional variations were observed in the overall distribution patterns, the predominance of blood group O and Rh-positive individuals remained consistent with findings reported in cisgender studies across different regions of Bangladesh and neighbouring countries. These results provide the first documented insight into the ABO and Rh blood group distribution among the third gender population in the Sylhet district of Bangladesh. Conclusion: The findings contribute to understanding the genetic structure and allelic frequency patterns within this underrepresented group. Moreover, they hold potential implications for transfusion medicine, population genetics, and public health planning, particularly in developing inclusive healthcare services that address the biological and social dimensions of the third gender community. Further studies could help to identify allelic variations with possible evolutionary influences on blood group frequencies of the third gender.