Genes and environmental factors associated with the severity of progression of rheumatoid arthritis

Abstract

Part I of this thesis starts with a description of the Leiden Early Arthritis Clinic, followed by chapters on predicting the progression from Undifferentiated Arthritis to Rheumatoid Arthritis (RA) and predicting the severity of RA by clinical information available early in the disease stage. In part II of this thesis, several studies to genetic factors underlying the differences in the severity of joint destruction, are presented. Most importantly, we report interesting associations between SNPs in the genes encoding Wnt-signalling proteins and the MMP-9 gene and progression of joint destruction. Part III of this thesis is devoted to ACPA-negative RA. Evidence is emerging that we should consider this a distinct pathofysiological entity from ACPA-positive RA. We also report the results of a Genome Wide Association Study (GWAS) to the radiographic progression of RA. In part IV of this thesis, we describe two studies to non-genetic factors that could influence the severity of RA. We did not find any clear seasonal differences for the season of RA onset. We also conclude that although smoking influences the long-term outcome of RA, the effect of smoking is not independent of ACPA-status.