IDENTIFICATION OF A NOVEL DRB1*08v ALLELE WHICH DIFFERS IN THE FIRST VARIABLE REGION FROM THE REMAINING DRB1*08 ALLELES.
SG Rodriguez-Marino, CL Crevling, G Coquillard, and T Tang.  Immunological Associates of Denver, Denver, CO and Naval Medical Research Institute/Georgetown University, Kensington, MD.


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Extensive polymorphism of HLA class II genes becomes evident in the clinical laboratory when DNA-based techniques rather than serologic assays are used as routine typing methods. A novel DRB1*08v allele was identified among National Marrow Donor Programâ (NMDP) volunteers during routine PCR-SSOP typing. The new sequence was confirmed by direct sequencing analysis. The novel allele was identified in an Asian Pacific Islander individual with DRB1*08v, *0901; DRB4*0103; DQA1*03, *0401; DQB1*03032, *0402 HLA class II phenotype. Amplified DNA using DRB generic primers revealed a new hybridization pattern in addition to the DRB1*0901 and a DRB4*01 alleles. The new allele shared polymorphisms with DRB1*0809 and *1415, but hybridization with probe 1005w was negative. As expected by negative hybridization with 1005w probe, DNA failed to amplify with the DRB1*08/*12 sequence group-specific primer set. Direct sequence analysis of exon 2 was performed using DNA amplified with two primer sets which specifically amplified the new sequence. Sequencing primers used were the PCR primers. The nucleotide sequence of the new allele was identical to the DRB1*0809 allele from codons 5 to 11 and from codons 13 to 94. Codon 12 encoded ATG(M) instead of ACG(T) which differs from DRB1*0809 and the rest of the DRB1*08 alleles. Furthermore, this polymorphism has not been identified in any other DRB1 allele and probably was the result of a point mutation event. The new sequence was submitted to the GenBank database and was assigned accession number AF049875. Frequency of this novel allele in different ethnic populations as well as the clinical impact of its mismatch on bone marrow transplant outcome remains to be addressed.