Researchers from the UK’s University of Nottingham and colleagues conducted a new study of the population of Taiwan, where there is a high rate of gout, and found that the condition clusters in families.
The risk of developing gout was largely linked to shared modifiable factors, such as lifestyle and diet, while having close relatives with the disease also appeared to increase the risk, but to a lesser extent.
They write about their findings in a recent online issue of Annals of the Rheumatic Diseases.
Gout is a form of inflammatory arthritis, characterized by acute pain that happens with no warning, and swelling in the affected joint – most commonly in the big toe. It is often accompanied by lumps around the joint and can lead to disability and loss of joint function.
There is also evidence that gout is linked with heart attack, stroke and kidney failure.
The disease is caused by deposits of monosodium urate crystals, due to there being too much uric acid in the blood.
Clusters in families suggest genetic cause
Evidence already exists that gout clusters in families, which points to a genetic cause. But this is queried by a classic twin study where researchers found there was a strong hereditary link to high uric acid but no evidence that the disease itself is inherited.
Taiwan has the highest rate of gout in the world, so for this new study the authors looked at data covering the whole of the country’s population – some 23 million people.
They identified 4.2 million families where gout is prevalent and found having first- and second-degree relatives with the disease increases the chances of having it.
Lead author Dr. Chang-Fu Kuo, of Nottingham’s School of Medicine and also of Chang Gung Memorial Hospital, Taoyuan, Taiwan, says:
“Our results confirm the clinical belief that gout strongly clusters within families. In Taiwan the risk of an individual with any first-degree relative suffering from gout is approximately twice that of the normal population.”
The team found that the risk of developing gout goes up with the number of first-degree relatives that have it.
Thus, having a twin brother with gout raises the risk of developing it 8-fold, but having a parent or child with it only raises it 2-fold.
Men and women affected differently
The study also shows that genetic factors appear to affect men and women differently.
“Genetic factors contribute one-third in men and one-fifth in women,” Dr. Kuo explains.
As well as the genetic risk, the study reveals that shared environmental factors also play a part, and these are also different in men and women.
The researchers say the findings have prompted further questions for future studies, which they suggest should include large-scale genetic profiling to identify susceptibility genes and further population studies in other countries to identify shared environmental risk factors within families.
In May 2012, another study published in the Annals of the Rheumatic Diseases suggested that foods rich in purines increase the risk of gout flare-up. Purines are found in a range of foods – meat and seafood in particular.