An Example of Anti‐Jra Causing Hemolytic Disease of the Newborn and Frequency of Jra Antigen in the Japanese Population

An example of anti-Jra which caused hemolytic disease of the newborn is reported. Two other examples of the antibody were detected in random screening of Japanese donors. In testing 19, 298 unrelated Japanese, 5 Jr(a-) individuals were found, i.e. an incidence of 0.0003 (0.03%); the corresponding gene frequencies were Jra 0.984 and Jr 0.016.