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

Background And Objectives: Kidd blood group system consists of two major antigens: Jk and Jk . Both the antigens are absent in individuals typed as Jk and may develop clinically significant anti-Jk3 antibody. Screening donors for provision of Jk blood is an ongoing task for blood centres with Jk blood units kept frozen for specific requirements. In 2016, we discovered a previously typed Jk donor to be Jk weak positive. Therefore, a study was conducted for our donors to verify Jk status and to reinforce our typing protocol.

Materials And Methods: In this experiment, donors previously typed and screened as Jk were tested with four antisera of Jk and Jk , and each with gel card for serology testing. Sequence analysis was performed for SLC14A1 gene for the detection of JK and weak alleles for genetic testing.

Results: Among the 30 samples, four were serologically identified as Jk(a+ ) and genotypically identified as heterozygous for the JK*01W.01 allele. The other 26 were confirmed to be Jk 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 Jk detection, but failed to give consistent results for weak Jk .

Conclusion: By combining the tube method and gel card method in serology, along with complementary genetic testing, the possibility of misinterpreting weak Jk expression was eliminated, and we were able to provide Jk blood for safe clinical transfusion.