Comparative analysis of the association of HLA-B*51 suballeles with Behçet's disease in patients of German and Turkish origin.

The distribution of the different HLA-B*51 suballeles among patients with Behçet's disease (BD) of German (n=33) and Turkish (n=92) origin in comparison to their presence in the respective ethnically matched healthy control groups (German: n=325, Turkish: n=93) was studied. HLA-B*51x was significantly increased in both patient groups in comparison to the controls (Germans: 58% vs. 12%, OR 9.76, P<0.001; Turkish: 75% vs. 25%, OR 9.13, P<0.001). Molecular subtyping of B*51x revealed HLA-B*51011 and B*5108 as the predominant suballeles in both patient groups and controls although with a slightly increased frequency of HLA-B*5108 in the diseased individuals. HLA-B*5105 was the only further HLA-B*51x subtype detected in one Turkish patient heterozygous also for HLA-B*5101. HLA-B*5107 although present in a Turkish as well as German control was absent in the patient groups. There was also a tendency towards a higher degree of homozygosity for HLA-B*51x in both patient groups versus the matched controls (Germans: 10% in patients vs. 2,5% in controls; Turkish: 27% in patients vs. 13% in controls). Our study further supports previous hypothesis of an association of BD with B51 suballeles which share amino-acid residues at positions 63 and 67 as well as at positions 77-83 for specific peptide binding and natural killer (NK)-cell interactions. This applies to HLA-B*5101 and B*5108, but not to HLA-B*5107 different at position 67, which could be negatively associated with BD.