Hemolytic disease of the newborn (anti-Kell)
| HDN due to anti-Kell alloimmunization | |
|---|---|
| Classification and external resources | |
| Specialty | pediatrics |
| ICD-10 | P55.8 |
| ICD-9-CM | 773.2 |
Hemolytic disease of the newborn (anti-Kell1) is the second most common cause of severe hemolytic disease of the newborn (HDN) after Rh disease. Anti-Kell1 is becoming relatively more important as prevention of Rh disease is also becoming more effective.
Hemolytic disease of the newborn (anti-Kell1) is caused by a mismatch between the Kell antigens of the mother and fetus. About 91% of the population are Kell1 negative and about 9% are Kell1 positive. A fraction of a percentage are homozygous for Kell1. Therefore, about 4.5% of babies born to a Kell1 negative mother are Kell1 positive.
The disease results when maternal antibodies to Kell1 are transferred to the fetus across the placental barrier, breaching immune privilege. These antibodies can cause severe anemia by interfering with the early proliferation of red blood cells as well as causing alloimmune hemolysis. Very severe disease can occur as early as 20 weeks gestation. Hydrops fetalis can also occur early. The finding of anti-Kell antibodies in an antenatal screening blood test (indirect Coombs test) is an indication for early referral to a specialist service for assessment, management and treatment.
Mothers who are negative for the Kell1 antigen develop antibodies after being exposed to red blood cells that are positive for Kell1. Over half of the cases of hemolytic disease of the newborn owing the anti-Kell antibodies are caused by multiple blood transfusions, with the remainder due to a previous pregnancy with a Kell1 positive baby.
Suggestions have been made that women of child bearing age or young girls should not be given a transfusion with Kell1 positive blood. Donated blood is not currently screened (in the U.S.A.) for the Kell blood group antigens as it is not considered cost effective at this time.
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