Case 3 depiction. In a patient with β-thalassemia intermedia with prior exposure to blood and negative antibody screen (case 3), the transfusion of red cell units matched only to Rh and Kell antigens led to the reemergence of anti-Fyb antibody and delayed hemolytic transfusion reaction. Regular transfusions were possible with extended phenotypic matching of red cell units. Anti-Fyb was no longer detectable after 4 years, though antibody screen remained positive intermittently due to other alloantibodies. IAT, indirect antiglobulin test.