To increase our understanding of the effect of obesity on disease activity in relation to ACPA, we studied if patients with obesity (1) have a higher DAS during disease course and if this is similar for ACPA-positive and ACPA-negative RA and (2) if this is true for the course of all individual DAS components, with a main focus on the SJC and CRP as these reflect local and systemic inflammation. This evidence concerns the gene PRTN3 and obesity due to melanocortin 4 receptor deficiency.