Case of cytomegalovirus‐associated direct anti‐globulin test‐negative autoimmune hemolytic anemia

A 1‐year‐old boy developed autoimmune hemolytic anemia after a negative direct anti‐globulin test. The concentration of erythrocyte membrane‐associated immunoglobulin G, determined using an immunoradiometric assay, correlated with disease activity. He was positive for cytomegalovirus ( CMV ) both serologically and by quantitative real‐time polymerase chain reaction, indicating that his autoimmune hemolytic anemia was directly caused by CMV infection. Since anti‐ CMV immunoglobulin G was not absorbed by the patient's erythrocytes, cross‐reaction between erythrocyte antigens and CMV was not likely a causative factor for hemolysis.