Serological and Molecular Characterization of Blood Group A2 in Pakistan

Objective: To determine the frequency of Blood Group A2 genotype among Group A Pakistani whole blood donors. Study Design: Cross-sectional study. Place and Duration of Study: Armed Forces Institute of Transfusion (AFIT), Rawalpindi Pakistan, from Jan 2019 to Jan 2020. Methodology: One thousand (1000) healthy and unrelated blood donors were selected. The blood samples were typed for ABO, and those of Blood Groups-A and AB were further subtyped with the help of anti-A1 lectin to categorize them as A1, non-A1, A1B and non-A1B Groups. Next, DNA of non-A1 samples was extracted, and a Polymerase Chain Reaction using sequence-specific primers (PCR-SSP) for type A2 was performed, followed by polyacrylamide gel electrophoresis (PAGE). Results: Among one thousand blood donors, 247(24.7%) were typed as Blood Group-A, 94(9.4%) as AB-Group, 339(33.9%) B-Group and 320(32%) O Group with variable strength of reaction with ABO antisera. A and AB Blood Groups were further sub-grouped as A1 202(20.2%), A1B 77(7.7%), non-A1 45(4.5%) and non-A1B 17(1.7%). Anti-A1 antibodies were detected in 6(13.3%) of non-A1 samples. PCR of non-A1 samples showed 32(12.9%) to be genotypically A2, and the remaining 13(5.2%) were not A2 and were not further resolved. Conclusion: Blood Group A2 is not a rare Subgroup in our population. PCR-SSP is a more specific technique than anti-A1 lectin for establishing the Blood Group status of an individual.