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Disease Profile

Crohn’s disease

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Ileitis; Enteritis; Granulomatous colitis;


Digestive Diseases


Crohn's disease is a type of inflammatory bowel disease (IBD), the general name for conditions that cause inflammation in the gastrointestinal (GI) tract. Common signs and symptoms include abdominal pain and cramping, diarrhea, and weight loss. Other general symptoms include feeling tired, nausea and loss of appetite, fever, and anemia. Complications of Crohn's disease may include intestinal blockage, fistulasanal fissures, ulcers, malnutrition, and inflammation in other areas of the body. Crohn's disease can occur in people of all age groups but is most often diagnosed in young adults.[1][2] The exact cause is unknown, but is thought to be due from a combination of certain genetic variations, changes in the immune system, and the presence of bacteria in the digestive tract.[1][2][3]  Many of the major genes related to Crohn disease, including NOD2ATG16L1IL23R, and IRGM, are involved in immune system function. The disease is not inherited but it appears to run in some families because in about 15% of the cases the disease is present in more than one relative.[3] 

Treatment is aimed at relieving symptoms and reducing inflammation, and may include diet and medication, but some people require surgery.[1][2] Surgery often involves removal of the diseased segment of bowel (resection), the two ends of healthy bowel are then joined together (anastomosis). In about 30% of people who have surgery for Crohn’s disease symptoms may come back within three years and up to 60% will have recurrence within ten years.[4]


Crohn's disease causes inflammation of the digestive or gastrointestinal (GI) tract. It usually occurs in the lower part of the small intestine, called the ileum, but it can affect any part of the digestive tract, from the mouth to the anus. The inflammation extends deep into the lining of the affected organ, which can cause abdominal pain and diarrhea.[1] Affected individuals may also have loss of appetite, weight loss, and fever.[3]

About one-third of individuals with Crohn's disease have symptoms outside of the intestines, which may include arthritis, uveitis (inflammation of the covering of the eye), skin lesions, and sacroilitis (inflammation of the large joints of the tail bone and pelvis).[5]

Symptoms of Crohn's disease may range from mild to severe. Most people will go through periods in which the disease flares up and causes symptoms, alternating with periods when symptoms disappear or decrease. People with Crohn’s disease who smoke tend to have more severe symptoms and more complications. In general, people with Crohn's disease lead active and productive lives.[1][5]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
Percent of people who have these symptoms is not available through HPO
Abdominal pain
Pain in stomach
Stomach pain

[ more ]

Crohn's disease
Watery stool
Growth delay
Delayed growth
Growth deficiency
Growth failure
Growth retardation
Poor growth
Retarded growth

[ more ]

Intestinal obstruction
Bowel obstruction
Intestinal blockage

[ more ]

Multifactorial inheritance
Recurrent aphthous stomatitis
Recurrent canker sores
Ulcerative colitis
Weight loss


The exact cause of Crohn's disease is not known, but it appears to be a multifactorial condition. This means that both genetic and environmental factors likely interact to predispose an individual to being affected. Studies suggest that Crohn's disease may result from a combination of certain genetic variations, changes in the immune system, and the presence of bacteria in the digestive tract.[3]

Recent studies have found that variations in specific genes, including the ATG16L1, IL23R, IRGM, and NOD2 genes, influence the risk of developing Crohn's disease. These genes provide instructions for making proteins that are involved in immune system function. Variations in any of these genes may disrupt the ability of intestinal cells to respond to bacteria, leading to chronic inflammation and thus the signs and symptoms of the condition. There may also be genetic variations in regions of chromosome 5 and chromosome 10 that contribute to an increased risk to develop Crohn's disease.[3]


A variety of tests are used to diagnose and monitor Crohn’s disease. A combination of tests is often needed because some symptoms of the condition are similar to other intestinal disorders such as irritable bowel syndrome and to another type of inflammatory bowel disease (IBD) called ulcerative colitis.[1] Tests used to narrow down the diagnosis may include blood tests, tissue tests, ultrasound, x-rays, CT scan, and/or endoscopy. A proper diagnosis also involves identifying the extent and severity of disease as well as any related complications.[9]


For information on the treatment of Crohn's disease, visit the following links:

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK):

Crohn's & Colitis Foundation of America: 

Complementary and Alternative Medicine (CAM) for Crohn's disease from the Crohn's & Colitis Foundation of America: 

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Learn more

    These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

    Where to Start

    • Just Like Me! , a Web site for kids and teens with ulcerative colitis or Crohn's disease sponsored by the Crohn's & Colitis Foundation of America (CCFA).
    • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
    • MedlinePlus Genetics contains information on Crohn's disease. This website is maintained by the National Library of Medicine.
    • The Merck Manuals Online Medical Library provides information on this condition for patients and caregivers.
    • The National Digestive Diseases Information Clearinghouse (NIDDK) offers information on this condition. Click on the link to view information on this topic.

      In-Depth Information

      • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
      • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Crohn's disease. Click on the link to view a sample search on this topic.


        1. Crohn's disease. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). September 2014; https://www.niddk.nih.gov/health-information/health-topics/digestive-diseases/crohns-disease/Pages/facts.aspx.
        2. Walfish AE & Sachar DB. Crohn Disease. Merck Manual Consumer Version. 2017; https://www.merckmanuals.com/home/digestive-disorders/inflammatory-bowel-diseases-ibd/crohn-disease?qt=&sc=&alt=.
        3. Crohn disease. Genetics Home Reference. 2018; https://ghr.nlm.nih.gov/condition/crohn-disease.
        4. What is Crohn's Disease?. Crohn's & Colitis Foundation of America. 2016; https://www.ccfa.org/what-are-crohns-and-colitis/what-is-crohns-disease/.
        5. Cummings S, Rubin D. The Complexity and Challenges of Genetic Counseling and Testing for Inflammatory Bowel Disease. Journal of Genetic Counseling. December 2006;
        6. What are complex or multifactorial disorders?. Genetics Home Reference. October 8, 2012; https://ghr.nlm.nih.gov/handbook/mutationsanddisorders/complexdisorders. Accessed 10/15/2012.
        7. Department of Human Genetics. Autoimmune disorders. Emory University School of Medicine. 2004; https://genetics.emory.edu/documents/resources/Emory_Human_Genetics_Autoimmune_Disorders.pdf. Accessed 2/7/2012.
        8. Crohn Disease. Genetics Home Reference (GHR) . August 2007; https://ghr.nlm.nih.gov/condition=crohndisease. Accessed 2/7/2012.
        9. Diagnosing Crohn's Disease and Ulcerative Colitis. Crohn's & Colitis Foundation of America. May 31, 2010; https://www.ccfa.org/resources/diagnosing-crohns-uc.html. Accessed 10/15/2012.

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