Characterization of psoriatic arthritis in South Africa studies on a single centre cohort

Abstract

This thesis describes the clinical, radiological and genetic associations of psoriatic arthritis in a single centre cohort in South Africa. The introduction discusses the various aspects of psoriasis and psoriatic arthritis(PsA). I also discuss the epidemiology, genetic and environmental factors associated with psoriatic arthritis. In chapter 2, we discuss the overall assessment of PsA and the importance of incorporating the dermatological manifestations in the holistic assessment of patients with this complex disease. The treatment of PsA using traditional DMARDs and novel therapies are discussed in chapter 3. In chapter 4, we discuss the clinical, biochemical and radiographic feature in our cohort. The CASPAR criteria had not been validated in a South African population previously. We undertook to validate this criteria in our cohort, and the findings are discussed in chapter 5. In chapter 6, we describe the complete absence of African black patients with SpA/PsA in our cohort and discuss some of the reasons for its rarity. Genetic studies support the concept that part of the disease mechanisms is shared between psoriasis and PsA. However, they also show that heritability is higher in PsA. GWAS studies have indeed identified several genes that have effect only in PsA and not psoriasis or have substantially larger effects in PsA. Clearly more genetic and functional studies are needed to unravel the genetic associations further and elucidate the functional relevance of genes residing in the GWAS-associated regions. In chapters 7 and 8 we study two candidate genetic polymorphisms for association with PsA