Different genes may be involved in distal and local sensitization: A genome-wide gene-based association study and...

Neuropathic pain symptoms and signs of increased pain sensitization in osteoarthritis (OA) patients may explain persistent pain after total joint replacement (TJR). Therefore, identifying genetic markers associated with pain sensitization and neuropathic-like pain phenotypes could be clinically important in identifying targets for early intervention.

We performed a genome-wide gene-based association study (GWGAS) using pressure pain detection thresholds (PPTs) from distal pain-free sites (anterior tibia), a measure of distal sensitization, and from proximal pain-affected sites (lateral joint line), a measure of local sensitization, in 320 knee OA participants from the Knee Pain and related health in the Community (KPIC) cohort. We next performed gene-based fixed-effects meta-analysis of PPTs and a neuropathic-like pain phenotype using genome-wide association study (GWAS) data from KPIC and from an independent cohort of 613 post-TJR participants, respectively.

The most significant genes associated with distal and local sensitization were OR5B3 and BRDT, respectively. We also found previously identified neuropathic pain-associated genes-KCNA1, MTOR, ADORA1 and SCN3B-associated with PPT at the anterior tibia and an inflammatory pain gene-PTAFR-associated with PPT at the lateral joint line. Meta-analysis results of anterior tibia and neuropathic-like pain phenotypes revealed genes associated with bone morphogenesis, neuro-inflammation, obesity, type 2 diabetes, cardiovascular disease and cognitive function.

Overall, our results suggest that different biological processes might be involved in distal and local sensitization, and common genetic mechanisms might be implicated in distal sensitization and neuropathic-like pain. Future studies are needed to replicate these findings.

To the best of our knowledge, this is the first GWAS for pain sensitization and the first gene-based meta-analysis of pain sensitization and neuropathic-like pain. Higher pain sensitization and neuropathic pain symptoms are associated with persistent pain after surgery hence, identifying genetic biomarkers and molecular pathways associated with these traits is clinically relevant.