#229
IDENTIFICATION AND CHARACTERIZATION OF TWO NEW HLA-DRB1*13 ALLELES DURING ROUTINE PCR-SEQUENCING BASED TYPING.
Gerald J. Coquillard, BS, CHT , Karyn Hartman BS, MT and Susana Rodriguez-Marino MD, PhD, Diplomate A . Chicago IL, USA, Northwestern University, Feinberg School of Medicine, Children
s Memorial Hospital, 60614, Pathology, HLA Laboratory .
This abstract describes two novel HLA-DRB1 alleles that were identified during routine sequencing-based typing (SBT) of two potential recipient and donors for a stem cell transplant (R-177 and R-222). R-177, a Caucasian male with a diagnosis of Non-Hodgkin’s Lymphoma, carries DRB1*1352 (AF499445) at the DRB1 locus. His father also carries the novel allele at this locus. R-222, an African-American male with a diagnosis of Sickle Cell Anemia, contains a DRB1*13variant (not-yet assigned by WHO, AY225520) at the DRB1 locus. His brother also carries the novel allele. DRB1*1352 differs from DRB1*130101 by a single non-synonymous nucleotide substitution at codon 37, causing an amino-acid residue change from Asparagine to Tyrosine (TAC instead of AAC). DRB1*13variant also differs from DRB1*130101 by a single non-synonymous nucleotide substitution, in this case at codon 32, causing an amino-acid residue change from Histidine to Tyrosine (TAT instead of CAT). Exon 2 for R177 and R222 was sequenced on an ABI Prism 3100 Genetic Analyzer (Applied Biosystems, Foster City, CA, USA) using allele-specific primers. The exon 2 for the novel alleles was entirely sequenced in both directions using the Big Dye Terminator Cycle Sequencing Ready Reaction Kit (Applied Biosystems). These findings underline the importance of performing complete DNA-based typing by SBT on all samples with ambiguous results to unequivocally identify allele types. In addition, these findings indicate that "assuming" allele types based on allele frequencies may not always be acceptable.