Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract. Although it can affect any part of the digestive tract (from the mouth to the anus), it almost always affects the lower end of the small intestine and the beginning of the large intestine.
CD is one of the most prevalent inflammatory bowel diseases along with ulcerative colitis. More than 3.5 million people worldwide suffer from inflammatory bowel diseases.
It is an autoimmune disease, a type of disorder in which the immune system becomes overactive and mistakenly attacks the body's own healthy tissues and organs.
Symptoms of Crohn's disease
This pathology, along with other autoimmune diseases such as lupus, is characterized by periods of activity during which symptoms become more acute and the clinical course worsens (commonly known as "flares") and phases of remission during which patients show clinical improvement.
The duration of each phase is unpredictable, and may vary both within and between patients. The most frequent symptoms manifested during "flares" are intestinal and those deriving from them:
- Abdominal pain
- Fissures and ulcers
- Tiredness and fatigue
- Lack of appetite and weight loss
- General malaise and weakness
- Rectal bleeding
Types of Crohn's disease
Depending on which part of the digestive tract is affected, we will speak of one type of Crohn's disease or another:
- Ileocolitis: according to the Crohn's Disease and Ulcerative Colitis Foundation (CCFA), it is the most common type. It is characterized by inflammation in the lower part of the small intestine, or ileum, and the large intestine, or colon.
- Ileitis: causes inflammation exclusively in the ileum.
- Crohn's colitis: causes inflammation exclusively in the large intestine.
Causes of Crohn's disease
The causes of Crohn's disease are unknown. It have been seen alterations in the microbiome of people with Crohn's disease.
And, what is the microbiome? The human gut contains a large number of microbes that normally remain stable over time; however, alterations in the microbiome sometimes occur. Several studies have correlated alterations in the microbiome (dysbiosis), with destabilization of the microbiome and also with various diseases such as CD.
However, most experts argue that the origin lies in some environmental factor (diet, stress, exposure to certain microorganisms, immune system status...) that triggers the inflammatory response in genetically susceptible individuals.
Genetics and Crohn's disease
Crohn's disease has a genetic basis. Several genes have been are associated with an increased risk of developing the disease.
Some of the major genes related to Crohn's disease are:
- NOD2/CARD5: This is the most studied gene associated with Crohn's disease. Mutations in this gene significantly increase the risk of developing the disease, especially in people of European descent. It is estimated that about 15% to 30% of patients with Crohn's disease have mutations in this gene.
- ATG16L1: Genetic variants in the ATG16L1 gene have also been associated with an increased risk of Crohn's disease. This gene is involved in the process of autophagy, which is important for the removal of bacteria and other damaged cellular materials. Defective variants of this gene can affect the normal function of the immune system and the response to intestinal bacteria.
- IL10RB: This gene encodes the interleukin-10 (IL-10) beta receptor protein. IL-10 is a cytokine with potent anti-inflammatory properties that plays a central role in regulating inflammation and immune response by limiting the host immune response to pathogens. This prevents damage to the host and maintains normal tissue homeostasis. Variants in this gene may alter the regulation of the immune response and predispose to chronic inflammation in the gastrointestinal tract.
At ADNTRO we analyze genetic markers in these genes and many other genes associated with Crohn's disease. Discover your genetic predisposition at ADNTRO.