In ACPA-negative RA patients, CRP levels did not significantly differ for patients with overweight or obesity compared with normal weight patients (β0.17, 95% CI − 1.82, 2.15 and β1.02, 95% CI − 1.29, 3.33, respectively; Fig. 2). The gene discussed is PRTN3; the disease is obesity due to melanocortin 4 receptor deficiency.