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.