Clinical Significance of Rare Maternal Anti Jk^a Antibody

We hereby report a rare case of HDFN because of antibody to Kidd (Jk) blood group system—anti Jk^a. An EDTA sample of a baby along with mother’s sample was received in the Department for Direct Antiglobulin Test (DAT) alongwith blood requisition for double volume exchange transfusion. On blood grouping, baby’s and mother’s blood group was found to be B Rh D positive. DAT with polyspecific anti human globulin (AHG) was positive. Screening of mother’s serum for irregular antibodies showed anti-Jk^a antibody. AHG phase titers using tube technique were 1:64. Mother was found to be Jk^a antigen negative; father and neonate were found to be Jk^a antigenpositive. Antibody was observed to be of IgG type on Dithiothreitol treatment. Baby had total serum bilirubin of 20.5 mg/dl on day 3 of life and phototherapy was started. Exchange transfusion was not required in the baby. The present case emphasises the significance of minor blood group antigens other than Rh blood group system as a cause of HDFN. Although HDFN due to Jk antibodies is rare, however, the clinician must be aware of the occurrence of these antibodies as they can lead to severe HDFN and persistent anemia in the infant.