Rheumatoid Arthritis (RA) is a chronic autoimmune disorder that affects approximately 0.5-1% of the population. RA leads to inflammation of the joints and leads to irreversible destruction of... Show moreRheumatoid Arthritis (RA) is a chronic autoimmune disorder that affects approximately 0.5-1% of the population. RA leads to inflammation of the joints and leads to irreversible destruction of joints with subsequently to significant morbidity, disability for patients. Remarkably the amount of joint destruction differs substantially between patients. Currently medication mainly aims at diminishing inflammation. Because joint destruction seems to develop even when the inflammation level is low, since RA is still not curable and finally because joint destruction is irreversible, joint destruction becomes an increasingly important feature in patients with RA. In this dissertation, different aspects of joint destruction in RA were investigated. To highlight the most important findings: first of all the heritability of joint destruction was demonstrated. In addition several genes were further studied. Two genetic findings were of most interest: IL2RA was associated with joint destruction. Since there is already medication available that aims at IL2RA, this finding creates a new treatment option for the nearby future. More intriguingly, SPAG16, an thus far with sperm association gene, appears to be relevant in joint destruction in RA as well. This put a totally new light on the gene. Naturally, most of the newly discovered associations will need further research before they can be applied in clinical practice. Show less