Blood Group: Kell

Common: Approximately 100% Caucasians and 80% Blacks are Jsa- and at risk for developing anti-Jsa. [1]

Causes HDN: Yes
Critical Titer: 
The first case of hydrops from anti-Jsa was reported in 2005. What is startling to note about this was that the mother's Indirect Coombs test was NEGATIVE despite the infant having hydrops and a positive direct coombs (strength of 3+). The woman had lost an infant before due to hydrops, the cause of which was never identified. Further testing revealed the woman to be Jsa- and the baby Jsa+. Both maternal and fetal blood reacted with Jsa+ cells and they were able to identify the antibody as anti-Jsa. Delayed onset anemia was found on day 14 and the infant was treated with a transfusion, phototherapy and erythropoietin. [2]

In addition to the red blood cells being hemolyzed, erythroid and myeloid precursors are inhibited. [2]

While Anti-Jsa does not always cause HDN require a transfusion [4], in some cases HDN due to anti-Jsa can cause anemia requiring a post birth transfusion. [3]  Anti-Jsa can cause delayed onset anemia as well [2].


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