Tumor necrosis factor-α -308 A/G gene polymorphism in children with juvenile idiopathic arthritis: relation to disease activity, damage, and functional status.

Abstract

The study aims to evaluate the clinical significance of serum levels of tumor necrosis factor alpha (TNF-α) and -308 A/G promoter polymorphism in juvenile idiopathic arthritis (JIA) patients and find any association to the subsets, clinical and laboratory features, disease activity, and damage as well as functional disability. Forty-eight JIA children and 30 controls were included in the present study. Juvenile arthritis disease activity score in 27 joints (JADAS-27) was calculated, juvenile arthritis damage index (JADI) was assessed, and Childhood Health Assessment Questionnaire (CHAQ) measured the functional status. Serum TNF-α was assayed by ELISA and gene (-308) promoter polymorphism was determined by polymerase chain reaction. The 48 JIA children (mean age 11.5±2.8years) were 13 systemic, 17 oligoarticular, and 18 polyarticular onset. The serum TNF-α was significantly higher in patients (90.4±6.3ng/ml) compared to control (3.5±2.6ng/ml) (p<0.0001) with a tendency to be higher in the polyarticular subtype. All controls had TNF-α -308 GG alleles. The frequency of GG genotype tended to be higher in systemic onset compared to oligoarticular and polyarticular subtypes. The serum TNF-α significantly correlated with JADAS-27 (r=0.32, p=0.03) and CHAQ (r=0.37, p=0.01) and negatively with the presence of GG alleles (r=-0.48, p=0.001). The GG alleles were significantly negatively associated with C-reactive protein (r=-0.32, p=0.03) with a tendency to negatively correlate with JADAS-27, CHAQ, and JADI-extrarticular (r=-0.28, p=0.06; r=-0.25, p=0.09 and r=-0.25, p=0.09, respectively). There is evidence of a possible influence of the -308 SNP promoter position on the production of TNF-α, the severity of JIA which may consequently influence the response to anti-TNF-α treatment.