RS35705950 polymorphism of MUC5B Gene: Association with Rheumatoid Arthritis and Interstitial lung disease in Tunisian Population.

Introduction: Interstitial lung disease (ILD) is the most common extra-articular manifestation in rheumatoid arthritis (RA). Studies have concluded that there is an association between rs35705950 polymorphism of the MUC5B gene and RA-ILD.

Aim: To explore this polymorphism in a cohort of Tunisian patients suffering from RA with or without ILD and stufdy its association to ILD during RA.

Methods: A case-control study involving 61 patients followed for RA, 26 with ILD and 35 without pulmonary involvement and 62 healthy controls. This was an association study between genetic marker and RA-ILD by genotyping the rs35705950 polymorphism using PCR-RFLP.

Results: No association was found between rs35705950 polymorphism and RA. However, the comparison of RA-ILD patients with controls showed a significant association with the allele frequencies of rs35705950 polymorphism (p=0.008; OR=2.61; CI [1.2-5.66]). Indeed, the minor T allele increased the risk of developing ILD by 2.61 for RA patients compared to the controls. Comparison of allele frequencies in RA-ILD patients and RA patients without ILD showed a significant association between the minor T allele of the studied polymorphism and RA-ILD (p= 0.02; OR= 2.66; CI [1.09-6.5]). In the adjusted model, this risk increased in case of smoking (p=0.025; OR=3,84; CI [1,13-13,08]) and/or female gender (p=0.013; OR = 4,63; CI [1,33-16,17]).

Conclusion: Our work has confirmed the role of the polymorphism of MUC5B promoter in the appearance of ILD during RA in Tunisian patients. This variant could be used to early detect preclinical ILD in patients with RA.