Interleukin 1 receptor antagonist gene polymorphism is associated with severe renal involvement and renal sequelae in Henoch-Schönlein purpura.

OBJECTIVE To assess the influence of interleukin 1 receptor antagonist gene polymorphism (IL1RN) in the incidence of Henoch-Schönlein purpura (HSP) and cutaneous leukocytoclastic angiitis (CLA) and to determine if implications exist with severe systemic complications of HSP, in particular with severe renal involvement and permanent renal dysfunction (renal sequelae). METHODS Patients from Northwest Spain with primary cutaneous vasculitis classified as HSP or hypersensitivity vasculitis (HV) according to proposed criteria were studied. Patients with HV were included if they had a biopsy proven small size blood vessel leukocytoclastic vasculitis limited to skin and also fulfilled the Chapel Hill Consensus Conference on the Nomenclature of Systemic Vasculitis definitions for CLA. All patients were required to have had at least 2 years' followup. Patients and ethnically matched controls were genotyped for IL-1 receptor antagonist intron 2 VNTR polymorphism. RESULTS We examined 96 Caucasian patients (58 HSP and 38 CLA) and 109 controls. No allele or genotype differences between the whole group of HSP or CLA patients and controls were observed. We found a significant association between carriage of IL-1 receptor antagonist allele 2 (ILRN*2) and severe renal involvement, manifested as nephrotic syndrome and/or renal insufficiency (p = 0.016), and permanent renal involvement (renal sequelae) (p = 0.012). CONCLUSION In unselected patients with cutaneous vasculitis, carriage of ILRN*2 alleles influences disease severity rather than susceptibility.