Novel HLA-A, -B, -C and -DRB1 alleles identified in the Australian New South Wales tissue typing laboratory.

HLA compatibility between patients and donors is a determining factor for the success of stem cell and solid organ transplantations. However, finding suitable donors remains challenging due to the highly polymorphic nature of HLA genes. Here we are describing 16 novel HLA-A, -B, -C and -DRB1 alleles identified over the period of 2 years. Fourteen differed from their closest reference allele sequence by single nucleotide substitutions detected in the coding regions and 13 contained polymorphism outside antigen recognition domains (exons 2 and 3 in class I and exon 2 in HLA class II). Two novel alleles, a non-sense substitution and a deletion of 2 bp resulted in two null alleles, while a substitution in a splice site resulted in an allele with questionable expression status. In HLA matching procedures, particularly in donor selection, it is important to determine alternatively expressed HLA alleles. Thirteen additional HLA-A, -B, -C and -DRB1 alleles detected as novel at the time of testing were already reported by other laboratories by the time of submission.