1022-lbp: Identification of new alleles and their impact on hematopoietic stem cell transplantat donor selection

Abstract

Aim Polymorphism of human leukocyte antigens (HLA) is the major barrier to hematopoietic stem cell transplantation (HCT). Advancement in DNA typing methods has significantly impacted donor selection for HCT recipients. The ImMunoGeneTics (IMGT)/HLA database, 7/25/2013, lists 9719 HLA and related alleles and continues to grow. We describe 3 patients with hematological malignancies who were evaluated for HCT work up. DNA from recipients A and B, carried single non-synonymous mutations that resulted in new alleles in DQB1 and A loci, respectively. In DNA from recipient C, a rare HLA-A allele was identified. Methods DNA was isolated from peripheral blood cells and buccal swabs by automated and manual methods. The HLA-A and -DQB1 genes were amplified by polymerase chain reaction (PCR) using primers specific for each loci and sequenced by Atria sequencing kits (Abbot Molecular, Des Plaines, IL) exons 2 through 4 for HLA-A and exons 2 and 3 for HLA-DQB1. Data was analyzed by Assign 3.6 SBT software (Abbot Molecular). Results DNA from buccal swabs confirmed each suspected mutation suggesting that mutations were carried by recipient’s genomic DNA and were not limited to malignant cells. Recipient A had a related sibling, which carried the same mutation and was 10/10 matched. Recipient B did not have related donors suitable for testing. The National Marrow Donor Registry (NMDP) search was unsuccessful in finding matched unrelated donors (MUD). For recipient C, 4 related donors were evaluated, 2 siblings, did not carry the mutation however, 2 sons, carried the rare allele. A search for MUD was initiated and 3 international donors were identified. Conclusions Identification of novel alleles are a common finding that can affect HCT donor searches. It is important to confirm the discovery by re-typing the loci from an alternative DNA source, especially in cases of patients with hematological malignancies. It is important that the laboratory works with the HCT program to identify best donors for these patients.