Sequencing based typing for HLA-C. Identification of three new alleles: Cw*0307, Cw*0502 and Cw*0504

HLA-C has been described as a transplantation locus in the unrelated bone m arrow transplantation setting, and noticeably the number of mismatches betw een HLA-A,-B,-DRB1 compatible pairs is considerably high. Sequencing based typing (SBT) is an accurate and efficient methodology utilised in the HLA c lass I and II allele level of resolution. SBT for HLA-C locus was applied o n a sample of 40 HLA-A,B,DRB1,DRB3/4/5,DQB1-compatible bone marrow recipien t-donor pairs, and 3 new HLA-C alleles have been found. Cw*0307, well defin ed by serology as Cw3, showed two amino acid changes at the NK motif 77-80 regarding all described Cw*03 alleles, N77K80 instead of S77N80. Two new Cw *05 alleles were described, Cw*0502 properly typed by serology and Cw*0504 that behaves as a short antigen. Cw*0502 differed from Cw*0501 by only one nucleotide at exon 3, that generated an amino acid replacement at codon 177 , K to E. Cw*0504 differs from Cw*0501 by two clustered amino acid position s (114 and 116) placed at the peptide binding site. The rate of new BLA-C a lleles found in this small series evidences a high grade of hidden HLA-C di versity in the Spanish population, particularly in the well-defined serolog ic specificities.