Arthritis What is it and what causes it? Matt Brown Professor and Director of Genomics Queensland University of Technology Matt.brown@qut.edu.au
What is Arthritis? • Any disease of joints • Divided into: – Immune-mediated arthritis eg rheumatoid arthritis, psoriatic arthritis, lupus, ankylosing spondylitis – Metabolic arthritis eg. Gout – ‘Wear and tear’ arthritis e.g. osteoarthritis – Infectious arthritis e.g Ross River Fever, septic arthritis And over 100 other forms of arthritis
How Common Is Arthritis? • Affects 3.5 million Australians – By 2050 will affect 7 million Australians • Is the major cause of both disability and chronic pain in Australia • Costs Australia $23.9 billion in medical costs and lost income Bates, et al. Arthritis and disability: Social Policy Research Centre, UNSW, Australia, 2014
What Makes You at Risk for Arthritis? • Genes – Either single genes or multiple genes operating in combination • Environment – Diet – Smoking – Occupation – Infections – …
Human Genetic Diseases • Single gene ‘monogenic’ diseases – e.g. cystic fibrosis, haemochromatosis, osteogenesis imperfecta – Generally rare – Each family usually has a different mutation, usually in the same gene – Evident inheritance from generation to generation
Monogenic forms of arthritis • Very rare (<0.5% of population) • Includes – Some types of • Metabolic arthritis – Gout – Chondrocalcinosis • Disorders of joint and cartilage formation • Blood disorders – Haemophilia – Sickle cell disease
Common ‘polygenic’ diseases • e.g. osteoarthritis, rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis • Different individuals have different genetic variants in different, but overlapping, sets of genes • Condition ‘runs in the family’ but transmission from generation to generation not so obvious
The Environment and Arthritis • Smoking – Increases risk of RA, AS – May reduce risk of OA • Alcohol – Increases risk of gout, OA • Weight – Increases risk of OA and psoriatic arthritis • Occupation – Farmers at higher risk of hip and knee OA
Do Gut Bacteria Cause Arthritis? • Compared gut bacteria in cases with ankylosing spondylitis with healthy controls • Cases have different gut bacteria to health controls Consistent with either disease • affecting the bacteria, or the bacteria causing the disease. Costello et al., Arthritis Rheumatol, 2015
Rehaume LM et al. Arthritis Rheumatol. 2014 Oct;66(10):2780-92.
Summary • Mostly the cause of arthritis is in your genes. • Environmental factors are also important, so you can do things to help prevent arthritis. • Most inflammatory arthritis is thought ultimately to be caused by infections triggering the immune system to attack joints – ?Can we use this to prevent or treat arthritis?
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