Allo‐Anti‐Chido in a Ch‐Positive Patient

Abstract
Allo‐anti‐Chido (Ch) was detected in a patient whose red cells typed as Ch+. The C4 allotype of the patient was A4,B2 which associates strongly with the Ch phenotype Ch:1,‐2,3,4,‐5,6. Anti‐Ch2 + Ch5 were the Ch specificities identified. Absence of only Ch2 and Ch5 determinants on the C4B protein allowed this unique immune response to blood transfusion.