Ethnicity-specific impact of HLA I/II genotypes on the risk of inhibitor development: data from Korean patients with severe hemophilia A.

Inhibitor development is the most serious complication in patients with hemophilia. We investigated association of HLA genotypes with inhibitor development in Korean patients with severe hemophilia A (HA). HLA genotyping was done in 100 patients with severe HA including 27 patients with inhibitors. The allele frequencies between inhibitor-positive and inhibitor-negative patients were compared. HLA class I alleles were not associated with the inhibitor status. In HLA class II, DRB1*15 [n = 100, odds ratio (OR) 0.217, P = 0.028] and DPB1*05:01 [OR 0.461, P = 0.026] were negatively associated with inhibitor development. In a subgroup of patients with intron 22 inversion, C*07:02 was positively associated with inhibitor development [n = 30, OR 5.500, P = 0.043]. In the subgroup of patients without intron 22 inversion, the negative association between DPB1*05:01 and inhibitor development was reinforced [n = 70, OR 0.327, P = 0.010], and positive association of DRB1*13:02 and DPB1*04:01 with inhibitor development was identified [OR 3.059, P = 0.037 for both]. Previously reported risk alleles were not consistently associated with inhibitor risk in our series. This study demonstrated the profile of HLA alleles associated with inhibitor risk in Korean patients with severe HA was different from that in patients of other ethnicities, which needs to be considered in risk assessment and management.