New research, announced recently at the 7th EULAR annual congress, reveals the Protein Tyrosine Phosphatase N22 (PTPN22) gene is associated not only with rheumatoid arthritis (RA) disease susceptibility, but also with disease progression, according to researchers from Norway and the Netherlands.
Whilst the missense polymorphism (1858C>T ; rs2476601) in the PTPN22 gene has recently been shown to be associated with risk of developing rheumatoid arthritis, as well as some other autoimmune diseases (such as lupus and type 1 diabetes), the potential influence of the gene on clinical outcomes has previously been unclear. As such, the study team aimed to investigate the extent to which the PTPN22 polymorphism was associated with the presence of autoantibodies and rate of radiographic progression in rheumatoid arthritis.
The team genotyped a cohort of 238 Norwegian rheumatoid arthritis patients (56% RF positive, aged between 20 to 70 years, with an average disease duration of 2.3 years). Radiographic damage was assessed by hand radiographs scored with the van der Heijde modified Sharp score (vdH Sharp score) by one reader.
Results from the study revealed RA association with carriage of the T allele (34.6 % in patients vs 21.4 % in controls; OR=1.94 (1.35-2.79), p= 0.0003) as well as an association between annual progression rate of vdH Sharp score and T-allele carriers (p=0.01).
No significant association was observed between the presence of the T-allele and either RF status (36% in RF+ vs 33% in RF-) or anti-CCP status (37% in anti-CCP+ vs 31% in anti-CCP-). To look for evidence of epistasis between PTPN22 and DRB1, the team also stratified for presence or absence of the shared epitope (SE), however no difference was seen between the two groups.
"Results from this study reveal the PTPN22 gene risk variant was associated with the progression rate for the articular damage" explained Dr. Benedicte Lie, Institute of Immunology, Rikshospitalet University Hospital, Oslo, Norway, and the study's lead author. "Our findings indicate that this candidate gene is associated not only with disease susceptibility, but also with disease progression – a potentially valuable discovery in the search for effective treatments to treat and ultimately prevent onset of rheumatoid arthritis" she continued.
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