Our aim was to explore the influence of 9-bp insertion/deletion and variable number of 9 bp elements (63/91) length polymorphism in noncoding interfering RNA and major promoter of DHFR gene on methotrexate (MTX) efficacy and toxicity in patients with rheumatoid arthritis (RA).
Response to the MTX therapy and adverse effects were estimated in 243 RA patients genotyped for the selected polymorphism.
The presence of allele 1 of analyzed polymorphism had significant protective effect against MTX toxicity (odds ratio: 0.37 [95% CI: 0.19-0.70]; p = 0.002). Results remained significant in multiple logistic regression analysis with the inclusion of disease and treatment features in the model (p = 0.03).
Polymorphism 63/91 in DHFR gene promoter can modulate the onset of MTX-related adverse effects in RA patients.