Crohn's disease

Crohn's disease (CD) is a chronic inflammatory condition of the digestive tract that progresses with flares and is one of the so-called inflammatory bowel diseases. The inflammation can affect different areas of the digestive tract depending on the individual. Its cause is unknown, although it is believed to be due to a combination of environmental, immune and genetic factors. Its overall prevalence is estimated at 0.4%.

The exact causes of Crohn's disease and its triggers are unknown. Research shows that it may result from a combination of environmental, immune and microbiological factors in genetically susceptible individuals. Important risk factors include:

  • Age: CD can develop at any age, but it usually begins during youth. Most people develop it before the age of 30.
  • Ethnicity: it is more common in people of Caucasian and Ashkenazi Jewish descent, although it can affect people of any ethnicity.
  • Smoking is the most important controllable risk factor associated with CD. In addition, smoking is also associated with a more severe form of the disease.
  • Nonsteroidal anti-inflammatory drugs. They can cause inflammation of the intestine, which can worsen the disease.
  • High-fat diet, which may increase the risk of the disease.

The pathogenesis of Crohn's disease is poorly understood, although studies point to a dysregulation of the immune response to environmental triggers in genetically susceptible individuals. In a GWAS-type study conducted in more than 40,000 cases and about 120,000 controls, more than 100 susceptibility loci were identified. Among the genes identified, many of them are involved in the regulation of the immune response, such as NOD2 or IL23R. In addition, genes coding for integrins capable of altering the response to an immune stimulus, such as ITGA4 and ITGB8, were identified. These discoveries open up the possibility of identifying possible therapeutic targets.

Symptoms

Crohn's disease usually has active periods (flares) with alternating asymptomatic phases, although in some people there are ongoing symptoms despite treatment. These symptoms vary depending on the area of the intestine affected, but usually include the following:

  • Diarrhea of more than 6 weeks evolution, in many cases, with blood.
  • Abdominal pain and weight loss.
  • Fatigue and general malaise.
  • Joint pain.
  • Development of perianal fistulas.
  • Inflammation of other regions such as skin, joints or liver.
  • Kidney stones.
  • Anemia.
  • Stunted growth, when initiated in children.

Some research suggests that stress may worsen or even trigger the onset of symptoms. In addition, in some people, certain foods may also worsen symptoms.

Prevention

Preventing the development of Crohn's disease is not possible because the exact causes of its onset are not known, although it is possible to act against certain risk factors that influence its development and aggravate the pathology, such as smoking. It has been proven that smoking increases the risk of developing this disorder, also increasing the risk of complications in those who suffer from the disease.

In patients diagnosed with CD, there are therapies that can help to significantly reduce their signs and symptoms and can even achieve some remission of the disease. In addition to the pharmacological and surgical treatments available, there are actions that can help prevent a flare-up or reduce symptoms:

  • Avoid carbonated beverages.
  • Avoid high-fiber foods.
  • Drink more fluids.
  • Eat smaller amounts of food more frequently.
  • Keep a food diary to help identify foods that may cause problems.

Number of observed variants

13.5 million variants

Number of risk loci analyzed in the study

104 loci

Bibliography

de Lange KM, Moutsianas L, Lee JC, et al. Genome-wide association study implicates immune activation of multiple integrin genes in inflammatory bowel disease. Nature Genetics. 2017 Feb;49(2):256-261.

National Institute of Diabetes and Digestive and Kidney Diseases (NIH) [April 2022]

Crohn´s and colitis foundation [April 2022]

Mayo Clinic [April 2022]

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