HLA-B and Behcet disease: To investigate if the HLA-B*51 or the rs76546355/rs116799036 risk allele status are associated with clinical and demographic characteristics of Iranian BD patients, we tested whether the characteristics have significantly different frequencies among B*51-positive (66.7% or 454 out of 681 patients) and B*51-negative cases (33.3% or 227 out of 681 patients), or between (AA + GA) patients when compared to GG patients (Table 5).