Does Anti‐Jra Cause Hemolytic Disease of the Newborn?

. A Jr(a-) Japanese female developed anti-Jra during her first pregnancy. Both father and infant red cells were Jr(a+), and anti-Jra was eluted from the infant's red cells. The antibody was determined to be IgGl. Hemolysis could not be definitively established from the clinical data. The pitfall of using the presence of jaundice as the sole evidence for hemolysis is emphasized. We conclude that the present case, and other previously reported cases, do not unequivocally establish that anti-Jra causes significant hemolytic diesease of the newborn (HDN). Amniocentesis probably should not be performed during the pregnancy of mothers sensitized to Jra antigen. Jra HDN is probably a mild disease, like ABO HDN.