Introduction:The presence of weak variants of blood type A represents a challenge in the practice of immunohematology for discrepancies in the time of the classification. It is common in blood banks to perform a forward and reverse typing for the purpose of confirming the blood type, but not all the people with a subgroup A2 have developed anti-A1 antibodies. Objective: We present a descriptive, observational and transversal study that establishes the proportion of subgroups of A antigen with the analysis of manual tube technique and monoclonal antibodies like anti-A, anti-A1 (Dolichus biflorus lectins extract) and anti-H. Methods: The analysis involved a total of 818 samples of voluntary blood donor, selected by random sampling, which were initially classified as 737 of Type A, and 81 as Type AB, with a confidence level of 95% (alpha error of 5% and 3% of precision). Results: The present study evaluated the existence of the subgroups A1, A2, A1B, A2B, A intermediate and A intB. Conclusions: It is recommended the identification of subgroups in different types of blood in the laboratory and blood banks.

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