Uncovering specific genetic-respiratory disease endotypes for rheumatoid arthritis risk

We aimed to identify specific genetic-respiratory disease endotypes for rheumatoid arthritis (RA) risk. This case-control study used the Mass General Brigham (MGB) and Mayo Clinic (MC) Biobanks for discovery and replication, respectively. We matched criteria-confirmed incident RA cases to four non-RA controls on age, sex and health record history. Genetic exposures included the top 11 RA risk alleles, and a validated human leucocyte antigen (HLA) genetic risk score (GRS). We identified seven respiratory diseases by codes. Using logistic regression models adjusting for potential confounders, we estimated Rs with 95% CIs for the interactions between genetic and respiratory exposures for RA risk. We identified 653 RA cases and 2607 controls in MGB, and 428 incident RA cases and 1712 non-RA controls in MC (mean age 64, 69% female). Respiratory diseases were associated with an increased risk of RA (OR 1.34, 95% CI 1.05, 1.71). Six out of 11 non-HLA RA risk alleles interacted strongly with specific respiratory diseases for RA risk, including NFKBIE and sinusitis (OR 5.49, 95% CI 1.56, 19.4 MGB; 5.26, 95% CI 2.00, 13.86 MC) and FAM167A and acute sinusitis for seronegative RA (OR 6.00, 95% CI 2.09, 17.24 MGB; 4.90, 95% CI 1.71, 14.1 MC). The RA HLA GRS interacted synergistically with interstitial lung disease for RA risk (OR 5.41, 95% CI 2.71, 10.8 in MC), with DPB1*02:01, DRB1*16:01 and DRB1*04:04 best predicting RA (positive predictive value 61%). Several genetic-respiratory disease interactions strongly drive RA onset. If confirmed, these novel associations may reflect RA endotypes that can facilitate individualised prevention, diagnosis and treatment.