I have a friend whose husband has Crohn's disease. She may be pregnant and is wondering what the likelihood is that her baby will have this disease. Is there a test that can diagnose Crohn's disease during pregnancy?
Crohn's disease, like most other autoimmune diseases, is thought to be a multifactorial condition. This means it is likely associated with the effects of multiple genes, in combination with lifestyle and environmental factors. Once an autoimmune disease is present in a family, other relatives may be at risk to develop the same autoimmune disease, or a different autoimmune disease. However, if an autoimmune diseases such as Crohn's disease occurs in a family, it does not necessarily mean that relatives will develop an autoimmune disease. Having an affected family member means that there may be a genetic predisposition in the family that could increase an individual's chance of developing an autoimmune disease. Thus, having an affected family member is considered a risk factor for Crohn's disease.
Last updated: 10/15/2012
What is the chance of a child developing Crohn's disease if a parent is affected by this condition?
Studies have shown that if one parent has this disease, each of his/her children has up to a 10% chance of developing the disease; if both parents have the disease, each of their children has up to a 50% chance of developing the disease. 
Last updated: 2/8/2012
Is prenatal testing available for Crohn's disease?
Because Crohn's disease is caused by many factors, no test can determine if an individual will definitely develop this condition. Genetic testing is available to determine if there is a disease-causing change (mutation) in the NOD2 gene, one of the genes that has been shown to be associated with an increased chance of developing Crohn's disease. Genetic testing may be available during pregnancy (prenatal diagnosis) to determine if a fetus has inherited a familial mutation in the NOD2 gene when a mutation has been identified in a relative. The finding of a mutation in the NOD2 gene does not diagnose Crohn's disease; it only indicates that there is an increased chance of developing this condition at some point in the future.
GeneTests is a web site that lists the names of laboratories that are performing genetic testing for Crohn's disease; currently, there is only one laboratory listed as offering prenatal diagnosis for this condition in the United States. To view the contact information for the clinical laboratories conducting testing, click the following link: Crohn's disease. [Please note: Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.]
Last updated: 2/8/2012
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