The critical region for Behçet disease in the human major histocompatibility complex is reduced to a 46-kb segment centromeric of HLA-B, by association analysis using refined microsatellite mapping.

The HLA-B51 allele is known to be associated with Behçet disease. Recently, we found a higher risk for Behçet disease in the MICA gene, 46 kb centromeric of HLA-B, by investigation of GCT repetitive polymorphism within exon 5 of MICA. The pathogenic gene causing Behçet disease, however, has remained uncertain. Here, eight polymorphic microsatellite markers, distributed over a 900-kb region surrounding the HLA-B locus, were subjected to association analysis for Behçet disease. Statistical studies of associated alleles detected on each microsatellite locus showed that the pathogenic gene for Behçet disease is most likely found within a 46-kb segment between the MICA and HLA-B genes. The results of this mapping study, and the results of an earlier study of ours, suggest that MICA is a strong candidate gene for the development of Behçet disease.