Mild Hemolytic Disease of the Newborn due to Anti‐Jk3: A Serologic Study of the Family's Kidd Antigens

Abstract
The first prospectiely followed case of hemolytic disease of the newborn due to anti-Jk3 alone is reported. A Samoan woman with known anti-JK3 was closely monitored during her 3rd pregancy. Because of elevated .DELTA.OD [change in optical density] values in the amniotic fluid and rising titer of serum antibody, labor was induced at 36 wk gestation. The cord red blood cells were coated with IgG, an anti-Jk3 was eluted from the cord cells and the placenta. A family study was done quantitating the expression of Kidd antigens by titrations and scores. Although titrations and scores were reported to identify cells carrying the silent allele Jk in the heterozygous state, in this family, dosage differences were noted with only 1 of 2 Jk-heterozygous daughters.