Genotyping and serotyping profiles showed weak Jka presentation for previously typed as Jknull donors.

Abstract

Kidd blood group system consists of two major antigens: Jka and Jkb . Both the antigens are absent in individuals typed as Jknull and may develop clinically significant anti-Jk3 antibody. Screening donors for provision of Jknull blood is an ongoing task for blood centres with Jknull blood units kept frozen for specific requirements. In 2016, we discovered a previously typed Jknull donor to be Jka weak positive. Therefore, a study was conducted for our donors to verify Jknull status and to reinforce our typing protocol. In this experiment, donors previously typed and screened as Jknull were tested with four antisera of Jka and Jkb , and each with gel card for serology testing. Sequence analysis was performed for SLC14A1 gene for the detection of JKnull and weak alleles for genetic testing. Among the 30 samples, four were serologically identified as Jk(a+w ) and genotypically identified as heterozygous for the JK*01W.01 allele. The other 26 were confirmed to be Jknull with JK*02N.01 as the most frequent allele. None of JK*B weak alleles were detected, but three were identified as false positives in the tube method. Gel card gave great accuracy for Jkb detection, but failed to give consistent results for weak Jka . By combining the tube method and gel card method in serology, along with complementary genetic testing, the possibility of misinterpreting weak Jka expression was eliminated, and we were able to provide Jknull blood for safe clinical transfusion.