Frequency of A2 and A2B Subgroups among Individuals with A and AB Blood Groups at a Multispeciality Centre in South Canara
Abstract: Background: The ABO blood group system is one of the most clinically significant blood group systems in transfusion medicine and comprises four major phenotypes: A, B, AB, and O. Blood group A is primarily divided into A1 and A2 subgroups, with A1 being the more common subgroup. Individuals with A2 or A2B subgroups may occasionally develop anti-A1 antibodies. Anti-A1 is generally considered clinically insignificant when reactive only at lower temperatures; however, antibodies reactive at or near 37°C may be clinically significant and may cause haemolytic transfusion reactions. Identification of A subgroups is therefore important for safe transfusion practice. Objectives: To determine the frequency of A2 and A2B subgroups among individuals with A and AB blood groups. Methods: A cross-sectional study was conducted among patients attending Mangala Hospital and Mangala Kidney Foundation, Mangaluru, Karnataka, India, from January 2024 to December 2024. ABO and RhD blood grouping data of 450 patients were analysed. Individuals belonging to blood groups A and AB were further evaluated for A1, A2, A1B, and A2B subgroups according to the laboratory protocol. Results: Among the 450 individuals studied, 183 (40.7%) were blood group O, 144 (32.0%) were blood group A, 90 (20.0%) were blood group B, and 33 (7.3%) were blood group AB. Regarding RhD status, 427 (94.9%) individuals were RhD positive and 23 (5.1%) were RhD negative. Thus, 177 (39.3%) individuals belonged to the A and AB blood groups. Among the 144 individuals with blood group A, 140 (97.2%) were A1 RhD positive, 1 (0.7%) was A2 RhD positive, and 3 (2.1%) were A1-negative, no A2-negative individual was identified. Overall, one individual was identified as A2-positive, corresponding to a frequency of 0.7% among individuals with blood group A. Among the 33 individuals with blood group AB, all 33 (100%) were A1B RhD positive, while no A2B subgroup was identified. Conclusion: A2 was an uncommon subgroup in the study population, while A2B was not identified among the AB blood group individuals studied. Appropriate identification of A subgroups may assist in the investigation of ABO discrepancies and support safe transfusion practices.
Keywords: ABO blood group, A<sub>2</sub> subgroup; A<sub>2</sub>B subgroup, anti-A<sub>1</sub>; blood grouping, transfusion medicine, immunohematology, South Canara
How to Cite?: Ashika Madonna DSouza1, Mithun Venugopal A, "Frequency of A2 and A2B Subgroups among Individuals with A and AB Blood Groups at a Multispeciality Centre in South Canara", Volume 15 Issue 10, October 2026, International Journal of Science and Research (IJSR), Pages: 870-873, https://www.ijsr.net/getabstract.php?paperid=SR261009062044, DOI: https://dx.doi.org/10.21275/SR261009062044