[Rare red blood group discovered by a blood group discrepancy: a case report].

ABO typing is essential for preventing ABO incompatibility transfusion reactions. Discrepancy exists when reactions in forward grouping do not match with reverse grouping. Any discrepancies reported should be investigated so that correct blood group is reported minimizing the chances of transfusion reaction. The most common causes of ABO discrepancy are cold autoantibodies and missing serum reactivity. We report a rare alloantibody anti-PP1Pk discovered during the resolution of a grouping difficulty with a positive control. Anti-PP1Pk is associated with hemolytic transfusion reactions. In our observation, we were faced with transfusional impasse because of the unavailability of a national rare blood bank or a compatible donor on the registry of individuals with a rare blood phenotype.