Frequency of ABO and Rhesus blood groups among blood donors in Lagos, Nigeria

Background : The ABO is a blood group system that is responsible for most blood transfusion reactions, transplant rejections and determining some forensic cases. The ABO and Rhesus blood group systems have been shown to show variations in different part of the world and race. Aim : The study is to show the frequency of ABO and Rhesus blood groups amongst blood donors in Lagos, Nigeria and confirm Hardy-Weinberg equilibrium. Methods : This is a two-year retrospective study of all blood donors from the two major tertiary health institutions in Lagos State between July 2004 and June 2006. Data from the blood bank records were extracted and analysed using SPSS version 20. Hardy-Weinberg equation was used to confirm if the population is in equilibrium. Results : In all, 11,911 donors were analysed and showed A+ 20.4%, A- 0.97%, B+ 16.7%, B- 0.87%, AB+ 2.2%, AB- 0.17%, O+ 55.6%, O- 3.1% and RhD positive frequency is 95.6%. The allelic frequency in this study is O – 0.7631, A - 0.1303, B – 0.1066 and Rh – 0.7786. There is no significant difference between the blood group distributions from the two institutions. Conclusion : Blood group O was the commonest blood group seen followed by group A. This is at variance with other studies in Nigeria where blood group B was the second commonest. The population was also found to be in Hardy-Weinberg equilibrium. The study provides important and reliable genogeographical information that can advance the fields of blood transfusion, organ transplantation and forensic medicine in Nigeria. Key words : Blood group, ABO, Rhesus, allelic frequency, Hardy-Weinberg equilibrium, transfusion reactions