The impact of position and type of amino acid substitution in HLA molecules was evaluated in pairs with HLA one-locus mismatch in HLA-C and -DPB1 separately. For example, Tyr9C-Ser9C indicated amino acid substitutions of position 9 in the HLA-C molecule in which the donor had tyrosine and the patient serine. The impact of position and kind of amino acid substitution in each HLA molecule was evaluated in pairs with HLA one locus mismatch in each HLA locus separately. Pairs that substituted a specific amino acid at each position were compared with amino acid matched pairs at that position.

No significant amino acid substitutions were found in HLA-DPB1.

All indicated results were concurrently significant in both base analysis and validation analysis using bootstrap resampling.

The 2 specific amino acid substitutions Tyr9C-Ser9C and Tyr99C-Phe99C were strongly linked in our sample.

An amino acid substitution that was significantly associated with a higher occurrence of severe acute GVHD in our previous study.⁸