Identification of the novel allele HLA-A*6813 in two members of a family of Syrian origin: implications for bone marrow transplantation

The identification of the new allele HLA-A*6813, which was found in a woman of Syrian origin and her son, is described. In the sequence analysis the n ew allele differs from A*68011 by positions 259 (A>G) and 261 (C>G) in exon 2. As the structure is thus identical to the HLA-A consensus sequence it i s likely that the new allele originated by gene conversion. At the protein level, the new allele has one amino acid difference from A*6801 (Asn63Glu), which results in a distinct banding pattern in one dimensional-isoelectric focusing. Amino acid residue 63 contributes to the formation of pocket A a nd B and is thus important for peptide binding, A*6813 was serologically de tectable only by two of six polyclonal, but by three monoclonal antisera. T he restricted serological A68 activity may be explained by altered peptide binding as presented peptides can affect the serological recognition of maj or histocompatibility complex (MHC) class I molecules. Moreover, our findin gs suggest that a possible mismatch with the other known A*68 variants may impair clinical outcome of bone marrow transplantation.