P081 Intron variation: The new allele pattern of 66 novel HLA class I alleles

Aim The aim of this study was to characterize the complete class I gene sequences of new class I alleles found in a population study of 1472 volunteers from the Argentina unrelated donor registry. Methods HLA-A, -B, -C alleles were amplified with primers annealing in the 5’ and 3’ UTRs and the sequences of exons and introns determined by next generation sequencing (NGS) with an Illumina Miseq using an in–house protocol and Conexio Assign software analysis. Initially class I and II amplicons were combined for sequencing; single locus sequencing of a second PCR amplicon was used to confirm variation. Allele sequences were submitted to the IPD-IMGT/HLA database. Results 1% of the 2944 alleles identified at each class I locus were novel. Three novel alleles were found multiple times. The majority (92%) differed by only a single nucleotide substitution from the known allele. Variants in noncoding regions predominated (79%) (T1). None of the intron variants appeared to impact RNA splicing motifs. The distribution of novel substitutions among introns is listed in T2. Unique substitutions, not shared by any other known allele at the locus, were found in 71% HLA-A, 58% HLA-B and 67% HLA-C novel alleles. Conclusions Sixty-six novel class I alleles were identified. The majority of substitutions were found in introns and appear to be random rather than resulting from gene conversion events. Download : Download high-res image (295KB) Download : Download full-size image Download : Download high-res image (73KB) Download : Download full-size image