Molecular aspects of a novel HLA-A*02 allele (A*0297): the first HLA class I allele mutated at codon 232.

We describe a new HLA-A*02 allele, identified in a cord blood unit and in her mother. Nucleotide sequence analysis showed the presence of a new HLA-A*02 allele identical to HLA-A*02010101 except for a non-synonymous nucleotide exchange in exon 4 modifying codon 232 from GAG (Glu) to GAC (Asp). No other human leucocyte antigen class I allele sequenced so far shows this triplet at codon 232. The amino acid exchange affects a position that is part of the membrane proximal domain of class I major histocompatibility complex (MHC), designated alpha 3, and involved in the interaction with CD8 molecule. Using molecular modelling approach, the interactions between different subunits of the native and mutated forms of MHC-I resulted in relevant changes.