Gout clusters within families, with increased risks being seen for individuals with affected relatives, while the heritability is higher among men than women, according to studies at the School of Medicine published in the Annals of the Rheumatic Diseases.
Scientists from the University of Nottingham looking at the whole population of Taiwan (23 million) with 4.2 million identifiable families have finally confirmed that gout clusters within families, with increased risks being seen for individuals with affected first and second degree relatives.
"Our results confirm the clinical belief that gout strongly clusters within families," said lead author, Dr Chang-fu Kuo. "In Taiwan the risk of an individual with any first-degree relative suffering from gout is approximately two fold that of the normal population."
The risk increases with the number of the first-degree relatives affected. Having a twin brother with gout carries an 8-fold risk, whereas having a parent/offspring with gout has a 2-fold risk. The study also demonstrates that in addition to the genetic risk, shared environment factors play a substantial role in the aetiology of gout. The influences of environmental and genetic factors on the risk of gout are different in men and women. Genetic factors contribute one-third in men and one-fifth in women.
Previous studies had suggested that gout often clusters within families, which is indirect evidence for a role of genetic factors in causation. However, one recent classic twin study paradoxically found strong heritability for hyperuricaemia but no evidence for heritability in gout.
Professor Michael Doherty, head of the Division of Rheumatology, Orthopaedics and Dermatology, said: "We found evidence for both shared environmental factors and genetic factors in predisposing to gout within families, with environmental factors contributing a higher proportional risk. Both genetic and environmental factors play a role in gout pathogenesis. Having an affected family member increases the risk but part of the risk comes from modifiable shared environmental factors such as diet and lifestyle."
The findings from this study open new questions for future research. In particular large-scale genetic profiling is needed to find susceptibility genes. Further epidemiology studies, including in other countries, to identify "shared environmental factors" within families contributing to the risk of gout will be very helpful.
Learn more about research on osteoarthritis and gout at the School of Medicine.
Posted on Monday 2nd December 2013