Gout

Gout or gouty disease is a pathology produced by an increase in the levels of uric acid in the blood (hyperuricemia) that causes the accumulation of urate crystals in a joint, causing sudden inflammation and pain. The joint most affected is the first metatarsophalangeal joint of the foot. Its prevalence is approximately 1% in developed countries.

The cause of gout is the appearance of urate crystals in the joint, which causes inflammation and pain. The formation of these crystals is caused by increased levels of uric acid in the blood, a product of the breakdown of purines, which are substances that are naturally present in the body and in many foods.

Among the risk factors associated with gouty disease are:

  • Diet. Excessive consumption of foods rich in purines such as red meat, seafood, sugary drinks, or alcohol significantly increases the risk of suffering from the disease.
  • In overweight people, the body produces more uric acid and the kidneys have less capacity to eliminate it.
  • Untreated medical conditions, such as hypertension, diabetes, obesity or kidney disease.
  • Certain medications, such as some diuretics, hypertension drugs or beta-blockers.
  • It tends to develop between the ages of 30 and 50.
  • Men are more likely to suffer from it, although, after menopause, women's risk becomes equal to that of men.

The genetic contribution to the progression of hyperuricemia remains relatively poorly understood. Although twin studies have been inconclusive as to the percentage heritability of the disease, what does seem to be clear is the important contribution of genetic predisposition to the development of elevated urate levels. A GWAS-type study carried out on almost 7000 cases and more than 480000 controls has identified some 30 associated loci. Among them, variants located in renal urate transporters, such as ABCG2 and SLC2A9, are of particular importance.

Symptoms

Essentially, gout produces arthritis (joint inflammation), almost always acutely and in a single joint, which can become intensely inflamed in a few hours. When the joint becomes inflamed it swells, its surface can become reddened, and it almost always becomes intensely painful, so that mobility can be affected by the pain itself. Sometimes the inflammation may be less intense and the discomfort more bearable.

The joints in which one can suffer gout attacks are diverse, but the most common are the big toe (which are called podagra attacks), instep, ankle, knee, wrist or some joints of the fingers of the hand.

Prevention

Gout is a largely preventable disease, mainly by avoiding risk factors. The recommended actions are the following:

  • Maintain a healthy weight. Obese people are more prone to suffer gout attacks.
  • Eat a healthy diet, avoiding the consumption of red meat, seafood, oily or blue fish, and favoring the intake of fruits and vegetables.
  • Avoid consumption of alcohol and carbonated beverages.
  • Keep a good health control, especially of pathologies such as hypertension, diabetes or heart disease.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

22 loci

Bibliography

Dönertaş HM, Fabian DK, Valenzuela MF, Partridge L, Thornton JM. Common genetic associations between age-related diseases. Nature Aging. 2021 Apr;1(4):400-412.

Tanya J, Dalbeth N, Stahl EA, Merriman T. An update on the genetics of hyperuricaemia and gout. Nature Reviews Rheumatology. 2018 Jun 14(6), 341–353.

National Health Service in England (NHS) [April 2022]

Centers for Disease Control and Prevention (CDC) [April 2022]

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