Possible association between NOD2 variants and joint surgery in psoriatic arthritis

Psoriatic arthritis (PsA) has been inconsistently associated with common NOD2 gene variants, although some of these studies did not include patient stratification by clinical phenotype.

To analyse the association between the three common NOD2 variants (R702W, G908R and L1007fs) and clinical phenotypes of PsA, particularly with surrogate markers of severe joint destruction.

A total of 183 unrelated PsA patients and 187 controls were included. Demographic, clinical, biological and immunological characteristics were collected. Genotypes for the three common NOD2 gene variants were obtained by PCR and direct sequencing.

NOD2 variants in PsA patients (7.6%) are just as prevalent as in healthy controls (7.5%). 18.5% of PsA patients carrying at least one NOD2 variant underwent joint surgery compared with 4.5% of those without these variants (p=0.019). Multivariate analysis confirmed this finding (OR 8.82, CI 1.7-46.3). There was no requirement for early surgery in patients carrying the NOD2 variants but there was an increased possibility of requiring surgery at similar times of disease duration. No other association with clinical features and NOD2 status carrier was found.

Common NOD2 gene variants are not associated with PsA, but might increase the risk of undergoing joint replacement surgery, suggesting that this autoinflammatory-associated gene could act as a phenotypic modifier gene in PsA patients by increasing the risk of joint destruction. Given the small number of PsA patients with joint surgery included, we consider our findings a new hypothesis that will need further testing.