Detection of an HLA-DRB1*03:105 allele in a patient on the waiting list for kidney transplantation in Colombia

Abstract

Introduction: In Colombia, patients in need of kidney transplants are evaluated using organ allocation criteria established by the National Institute of Health. HLA typing must be performed with medium-resolution techniques. Priority is given to minimizing incompatibility at the HLA-DR locus over the A, B, and DQ loci. Data are reported with serological equivalence for each locus, in the national system called REDDATA, for recipient selection. We analyzed a potential kidney transplant recipient for HLA-A, B, C, DRB1, and DQB1 using Luminex technology. The typing resulted in an HLA-DRB103:105/10 outcome. The DRB103:105 allele has no serological equivalence, so a sequence homology analysis was conducted, and it was recommended to include it in the database as HLA-DR17 due to its homology.

Methods: Case of a patient on the kidney transplant waiting list. Intermediate-resolution HLA typing was performed using Immucor Corp kits and read on a Luminex 200 instrument. The results were corroborated by Sanger sequencing of the 2nd exon of HLA-DRB1 using the 3.1 BigDye Terminator cycle sequencing kit on an ABI 3500 instrument.

Results: The patient's typing yielded HLA-A30/32, HLA-B18/42, HLA-C05/17, HLA-DRB103/10, HLA-DQB103/05, with the HLA-DRB103:105 allele being one of the alleles present. The typing through Sanger sequencing of the 2nd exon of HLA-DRB1 yielded an identical result.

Conclusions: To date, the HLA-DRB103:105 allele lacks serological equivalence, which hindered the data entry into the REDDATA system. This is the first time we have detected an HLA-DRB103:105 allele in over 30,000 processed samples. The HLA-DRB103:105 allele was reported in 2014 in the IPD-IMGT/HLA database, entry HLA11608, without associated geographical location or ethnicity. This allele is reported on allelefrequencies.net in two haplotypes from Chile. Based on the sequence alignment of the HLA-DRB103:105 allele, it was recommended to be reported as a serological equivalent of HLA-DR17.