Fetal and neonatal anemia associated with anti-Jr(a) : a case report showing a poorly hemolytic mechanism.

Although recently published case reports suggest the significance of Jr(a) alloimmunization in the obstetric setting, the involved mechanism still remains unclear. Here we report a case of severe fetal and neonatal anemia associated with anti-Jr(a) alloimmunization, which was successfully managed using Doppler assessment of peak systolic velocity of the fetal middle cerebral artery (MCA-PSV). A Japanese woman with anti-Jr(a) (titer 1024) was referred to our department at 20 weeks' gestation.

Collaborative study of irregular erythrocyte antibodies in Japan: results from the Japanese study group of allo-immunity and antigen diversity in Asian populations.

As a national study, we evaluated the frequencies of irregular erythrocyte antibodies (Abs) by gender and history of transfusion or pregnancy. In total, data from 248,785 patients were analyzed, from whom 4222 irregular erythrocyte Abs were detected in 3554 cases (1.43%).