Characterization of four new HLA alleles: HLA-B*15:01:18, HLA-B*44:110, HLA-C*04:01:22 and HLA-DQB 1*05:14 J. Heyder ∗ , A. Heinold, G. Fiedler, G. Opelz & T. H. Tran Department of Transplantation Immunology, Institute of Immunology, University of Heidelberg, Heidelberg, Germany * Present address: Institute of Legal Medicine, University of Munich, Munich, Germany Key words: HLA-B*15:01:18 ; HLA-B*44:110 ; HLA-C*04:01:22; HLA-DQB1*05:14; PCR-SBT We describe four novel HLA alleles, HLA-B*15:01:18, HLA-B*44:110, HLA-C*04:01:22 and HLA-DQB1*05:14. Four novel human leukocyte antigens (HLA)-B*15:01:18 (EMBL; FN689350), -B*44:110 (EMBL; FN689351), - C*04:01:22 (EMBL; FN995095) and -DQB1*05:14 (Gen- bank, HE584761) were identified by polymerase chain reac- tion sequence-based typing (PCR-SBT) of three unrelated hematopoietic stem cell donors and a deceased kidney donor. All donors were of Caucasoid origin. HLA-B*15:01:18 differs from HLA-B*15:01:01:01 by a single nucleotide exchange (G > A) at position 902 (codon 152) in exon 3 (Figure 1A). This does not result in a change of the amino acid coding (glutamic acid). Analyzing the sequences of all known HLA class I alleles showed that only B*49:01:02 showed the sequence motif ‘GAA’ at codon 152 as seen in the new allele B*15:01:18. Because B*49:01:02 has a low allele frequency, we hypothesize that the novel allele B*15:01:18 has emerged from a point mutation rather than from a crossover between B*15:01:01:01 and B*49:01:02. The complete typing of the female stem cell donor was A*02:01, *03:01 ; B*07:02, *15:01:18 ; C*03:04, *07:02 ; DRB1*07, *11 and DQB1*02:02, *03:01. Based on linkage disequilibrium information for the most closely related allele B*15:01:01:01, the B*15:01:18 -bearing haplotype could be A*02:01 – B*15:01 – C*03:04 (1). Compared with HLA-B*44:03:01, HLA-B*44:110 has a non-synonymous nucleotide exchange (G > C) at position 735 in exon 3 (Figure 1B). This alters the amino acid coding from arginine to serine at codon 97. Residue 97 is part of the peptide-binding pocket of HLA-B molecules (2). An amino acid exchange of arginine with a charged polar residue to serine with an uncharged polar character © 2011 John Wiley & Sons A/S 209 Tissue Antigens, 2012, 79, 204–217