[Hemolytic disease of the newborn caused by maternal anti-Di(a): a case report in Taiwan].

The first case of hemolytic disease of the newborn (HDN) possibly caused by anti-Di(a) in a Chinese infant in Taiwan is reported. The mother had two pregnancies before but no history of blood transfusion. Her first male infant was normal, but her second full-term male one developed mild jaundice soon after birth, and the total bilirubin level was 12.1 mg/dL, 18.3 mg/dL, 23.6 mg/dL at 24 hours, 48 hours, and 72 hours of age, respectively. Total bilirubin was 9.1 mg/dL on the eighth day after receiving phototherapy and compatible blood exchange transfusion. The infant recovered uneventfully. The immunohematological study revealed that the mother was group AB, Rh (D)+; Di(a - b+), the father was group O, Rh (D)+; Di(a + b+), the infant boy and his 2-year-old brother were group B, Rh(D)+; Di(a + b+). The direct antiglobulin test (DAT) on the infant red cells was positive (4+ with polyspecific AHG; 4+ with anti-IgG). The maternal serum and infant's eluate from red blood cells showed negative reactions in routine antibody detection tests, but they contained alloantibody reacting against the Di(a+) cells by the manual polybrene test (MP) and indirect antiglobulin test (IAT) in AHG phase. The anti-Di(a) titers in the mother's serum was MP 1:256 and AHG 1:256, and in the infant's eluate was MP 1:128 and AHC 1:64 against Di(a + b+) cells. Based on the above results we conclude that the jaundice in this newborn baby was caused by maternal anti-Di(a) which was most likely induced by previous pregnancy. In conclusion, Diego blood group is a system of high value in anthropology because it accounts for the Mongoloid origin of American Indians, Japanese and Chinese. Anti-Di(a) may cause HDN, as in our case of HDN due to maternal anti-Di(a) in a Chinese infant. But in Europe and America, where practically all people are Di(a - b+) phenotypes, the system seems of no interest in parental studies as well as in blood transfusions. Owing to the Di(a) antigen is of higher incidence in Chinese population, we suggest that the Diego system should be involved in routine compatibility testing or antibody identification problems in parental studies and in blood transfusions in Taiwan.