Association of C35T polymorphism in dihydrofolate reductase gene with toxicity of methotrexate in rheumatoid arthritis patients

ABSTRACT

Background: Methotrexate (MTX), a folate analogue, is the most commonly used disease-modifying drug in the treatment of rheumatoid arthritis (RA). However, high interindividual differences in drug response are present among RA patients.Research design and methods: In a group of 234 RA patients treated with MTX, we investigated whether rs1650697 polymorphism in DHFR gene may have an impact on MTX efficacy and/or adverse drug effects (ADEs). Relative DAS28 values (rDAS28) were used for the estimation of MTX therapy and all ADEs were recorded. Patients were genotyped for selected polymorphism by real-time PCR method.

Results: According to the European League Against Rheumatism criteria after 6 months of MTX therapy, 196 patients (83.8%) were classified as responders (25 (10.7%) were good and 171 (73.1%) were moderate) and 38 patients (16.2%) as nonresponders. ADEs were observed in 55 patients (23.5%).

Conclusions: Our results showed that the presence of T allele might be protective against MTX hepatotoxicity measured by transaminase levels (p = 0.05). Furthermore, among patients who also received low-dose corticosteroids, we have found a lower rDAS value in patients with CC genotype (p = 0.039).

KEYWORDS:

• DHFR
• genetic polymorphism
• methotrexate
• pharmacogenetics
• rheumatoid arthritis
• toxicity

Author contributions

The paper was written by DV and BJ, who also designed the experiment and conducted molecular-genetic analysis together with BP. VM, TD, IN, and NM participated in the study design. The manuscript was commented and revised by TD and NM. VM, ND, and VB analyzed the clinical assessment data. MK participated in the statistical analysis of the collected data.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This study was funded by the Serbian Ministry of Education, Science and Technological Development (Grant 175091).