DISTRIBUTION OF ABO BLOOD GROUPS, RH SUBTYPES, AND KELL ANTIGEN AMONG BLOOD DONORS AT A TERTIARY CARE CENTRE IN ALMORA

Background: The ABO, Rh, and Kell blood group systems are among the most clinically important blood group systemsbecause of their strong immunogenicity and their role in transfusion medicine. Transfusion of red blood cells expressingincompatible Rh or Kell antigens may result in alloimmunization, which can complicate future transfusions and adverselyaffect patient outcomes. Consequently, understanding the regional distribution of ABO, Rh, and Kell antigens is essential fordeveloping effective antigen-matching strategies, reducing the likelihood of alloantibody formation and maintaining adequateblood stocks in the blood centre. Accordingly, this study was designed to determine the distribution of ABO blood groups, Rhantigens, and Kell antigen among blood donors in the local population and to compare their frequencies across different studygroups. Materials and Methods: This cross-sectional study was carried out at the blood centre of a tertiary care medicalinstitute in Almora, Uttarakhand. Donor records spanning the period from January 2025 to June 2026 were retrospectivelyreviewed to determine the distribution and prevalence of ABO, Rh, and Kell antigens. Results: A total of 3,102 blood donorswere evaluated in this study, comprising 94% males and 6% females. Rh-D positivity was observed in 94.4% of the donorpopulation. Among the ABO blood groups, group A was the most prevalent (30.7%), followed by B (30.0%), O (27.3%), andAB (12.0%). Regarding Rh antigen distribution, the e antigen showed the highest frequency (98.71%), followed by D(94.42%), C (88.78%), c (56.87%), and E (19.34%). The prevalence of Kell (K) antigen was 1.64%. Among Rh-D-positivedonors, the most common Rh phenotype was R1R1 (DCCee), accounting for 41.5% of cases, whereas among Rh-D-negativedonors, the predominant phenotype was rr (ddccee), observed in 4.8% of donors. Conclusion: The observed variation in thedistribution of Rh and Kell antigens, along with Rh phenotypes among blood donors, emphasizes the importance ofimplementing appropriate transfusion strategies. Providing antigen-matched blood components may help minimize the risk ofalloimmunization, particularly in patients requiring repeated transfusions and in pregnant women.