174-P

Abstract

Aim A 20 year-old female diagnosed with AML was HLA typed and a registry search for an unrelated donor was initiated. The HLA typing was A ∗ 11:01, ∗ 24:02; B ∗ 08:01,∗48:01; C ∗ 07:01, ∗ 08:03; DRB1 ∗ 03:01, ∗ 12:01; DRB3 ∗ 01, ∗ 01; DQB1 ∗ 02:01, ∗ 03:01 as per SSO and SSP. High resolution extended DRB1 and DQB1 typing of five potential unrelated donors were performed by the HLA Laboratory at Canadian Blood Services for this patient by SBT. The typing report indicated a possible new DQB1 allele for all donors tested. Their report indicated that the closest genotype was DQB1 ∗ 02:01:01, ∗ 03:01:01 except for a single nucleotide mismatch in exon 3 at codon 175 from GTG (encoding for valine) to ATG (encoding for methionine). Methods HLA typing was performed using Luminex SSO (One Lambda), high-resolution SSP (Olerup, One Lambda), and SBT (Life Technologies, Abbott Molecular). Results Our lab tested the patient and two other unrelated donors received in the lab. All three samples contained the same DQ change in codon 175. We have also tested other samples with similar DRB1, DRB3, and DQB1 haplotypes—with no nucleotide substitution at codon 175 [ Table 1 ]. Conclusions We are inferring that the most likely origin of this new DQ allele is from the DQB1 ∗ 03 as a part of the B ∗ 48:01; DRB1 ∗ 12:01; DRB3 ∗ 01; DQB1 ∗ 03:01 haplotype, and not from the DQB1 ∗ 02:01. We also hypothesize that this new DQ is perhaps a common DQ associated with this B48-DR12-DR52-DQ7 haplotype, as no change in exon 3 noted with other similar haplotypes tested. We believe that any patients and potential donors with a similar haplotype should be tested by SBT to confirm the presence or absence of this particular nucleotide base pair substitution at codon 175.