Human leukocyte antigen (HLA) typing in the patient disclosed the DRB1*11 allele, which has been reported to be associated with HSP, but the brother proved negative, suggesting that this allele was irrelevant to the HSP pathogenesis.
This study demonstrates that susceptibility to HS also has a genetic origin: on one hand, the presence of DRB1*01 or DRB1*11 makes disease onset easier; on the other hand, DRB1*07 could induce some resistance to the disease.