To assess the effect of a functional polymorphism (676T>G, M196R) in the tumour necrosis factor receptor super family 1b (TNFSF1b) gene on disease activity, radiological joint damage and response to infliximab and adalimumab treatment in patients with rheumatoid arthritis (RA).
Two cohorts of patients with RA were genotyped for the 676T>G polymorphism (rs1061622) in exon 6 of the TNFSF1b gene by restriction fragment length polymorphism analysis. One cohort (n = 234) included patients from the Dutch Rheumatoid Arthritis Monitoring register with detailed information on their response to anti-TNF therapy (infliximab and adalimumab), the other cohort comprised patients from a long-term observational early inception cohort at our centre (n = 248).
The 676T>G polymorphism was not associated with anti-TNF response after 3 or 6 months of treatment. Linear regression analysis showed no significant difference in the progression of radiological joint damage during the first 3 and 6 years of disease between the three genotype groups (TT, TG and GG). Additionally, no difference in mean disease activity between genotypes was seen after 3 and 6 years of disease.
Despite its demonstrated functionality, the 676T>G polymorphism in the TNFSF1b gene does not have a major role in either the response to anti-TNF therapy or in the disease severity or radiological progression in RA.