Lack of association between interleukin-6 promoter polymorphism at position-174 and Henoch-Schonlein purpura

Objective. To assess whether polymorphism of the interleukin (IL)-6 gene at the position -174 was implicated in the incidence of Henoch-Schonlein purpura (HSP). A further objective was to determine if any relationship existed with severe systemic complications of HSP, in particular with severe renal and gastrointestinal involvement Methods. Unselected patients from Northwest Spain with primary cutaneous vasculitis classified as HSP according to proposed criteria were studied. All patients included in the present study were required to have had at least 2 year's follow-up. Patients and controls were genotyped for a single biallelic (G/C) nucleotide polymorphism in the promoter region at the position -174 of the IL-6 gene by a polymerase reaction chain-restriction fragment length polymorphism (PCR-RFLP) method. Results. Forty-six Caucasian HSP patients and 124 healthy matched controls were studied. No allele or genotype differences between the whole group of HSP and controls were observed. This was also the case when HSP patients were stratified by the presence of gastrointestinal complications, nephritis, and permanent renal involvement (renal sequelae). Conclusions. The polymorphism in IL-6 gene promoter (-174 G/C) does not appear to be a genetic risk factor for HSP in Northwest Spain.