Identification of novel DRB1*13 (DRB1*1333), DRB1*04 (DRB1*0426) and DRB5* (DRB5*0109) alleles

Three novel HLA class II alleles (DRB1*1333, DRB1*0426, DRB5*0109) are described here. The 3 novel alleles were initially detected as previously unidentified SSO hybridization patterns using the CANTYPE reverse hybridization assay. Sequences were determined by cloning/sequencing. DRB1*1333 is identical to DRB1*1303 except for a single nucleotide substitution (ACC-->AAC), changing codon 77 from Thr to Asn. This polymorphism is typical for DRB1*03 alleles. DRB1*0426 is identical to DRB1*0401 except for a single nucleotide substitution (GCC-->ACC) at codon 58, changing the encoded Ala to Thr. DRB5*0109 is identical to DRB5*0101, except for a single nucleotide substitution (GAC-->AAC), changing codon 70 from Asp to Asn. Both latter polymorphisms were so far undetected in DRB alleles. DRB1*1333 could have arisen from a gene conversion event, but DRB1*0426 and DRB5*0109 most likely were generated by point mutation events. For all 3 alleles, the sequence was confirmed by the original hybridization pattern (DRB1*1333) or by hybridization to a newly designed probe (DRB1*0426 and DRB5*0109). Ethnic backgrounds were Lebanese for DRB1*1333 and Caucasian for DRB1*0426 and DRB5*0109.