TNF-<b><i>α</i></b>Polymorphisms in Juvenile Idiopathic Arthritis: Which Potential Clinical Implications?

Abstract

Whether tumor necrosis factor alpha (TNF- α ) gene polymorphisms (SNPs) influence disease susceptibility and treatment of patients with juvenile idiopathic arthritis (JIA) is presently uncertain. TNF- α is one of the most important cytokine involved in JIA pathogenesis. Several single nucleotide polymorphisms (SNPs) have been identified within the region of the TNF- α gene but only a very small minority have proven functional consequences and have been associated with susceptibility to JIA. An association between some TNF- α SNPs and adult rheumatoid arthritis (RA) susceptibility, severity and clinical response to anti-TNF- α treatment has been reported. The most frenquetly studied TNF- α SNP is located at −308 position, where a substitution of the G allele with the rare A allele has been found. The presence of the allele −308A is associated to JIA and to a poor prognosis. Besides, the −308G genotype has been associated with a better response to anti-TNF- α therapy in JIA patients, confirming adult data. Psoriatic and oligoarticular arthritis are significantly associated to the −238 SNP only in some works. Studies considering other SNPs are conflicting and inconclusive. Large scale studies are required to define the contribution of TNF- α gene products to disease pathogenesis and anti-TNF- α therapeutic efficacy in JIA.