Crohn Disease

Is Testing Right for Me? I Have My Test Results

Crohn Disease

Genetics of Crohn Disease

Doctors aren't sure exactly what causes Crohn disease. They think Crohn disease results from a combination of your genes, your immune system, and germs in your digestive tract that trigger a reaction.

Researchers have found a number of genes that seem to play a role in Crohn disease. Changes in a gene called NOD2/CARD15 increase your risk to get Crohn disease, and they are associated with worse forms of disease. There are other genes that also play a role in Crohn disease, but less is known about them.

Genetic testing for Crohn disease can find gene changes that are associated with a higher chance to get Crohn disease. Having one or two gene changes does not guarantee that you will develop the disease. If testing finds two gene changes and you do get Crohn disease, you may have a higher chance to have a more severe type of disease. Your disease may start at a younger age than average. It may be more likely to cause narrowing of the GI tract. You may need more treatment, such as medicines and surgery, to prevent long-term health issues.

Normal test results can't rule out Crohn disease. Genetic testing only finds a change in about half of all people with Crohn disease. If your results are normal, your doctor will continue to treat you based on your symptoms.

Next: Who Should Consider Testing for Crohn Disease?

To find out if genetic testing might change your medical care, check the box below that best describes you.

I think I might have Crohn disease because I have some of the symptoms, but I haven't seen a doctor yet.

I've been tested for disease, and I definitely have it.

I've been tested for Chron disease, but the results weren't clear. My doctor isn't sure whether I have it.

I'm at-risk for Crohn disease because a close family member has it. I don't have any symptoms of it right now.

I'm at-risk for Crohn disease because I'm Ashkenazi Jewish. I don't have any symptoms of it right now.

I don't have any symptoms or risk factors for Crohn disease, but I'm worried about whether I'll get it.

You told us that you think you might have Crohn disease, but you haven't seen a doctor yet. A genetic test is not the first step to diagnosing Crohn disease. If you have symptoms that could be Crohn disease, it is important for you to see a doctor. The doctor will ask you more about your symptoms, review your family and medical history, and order tests as needed.

You told us that you definitely have Crohn disease based on testing you've had done. Genetic testing may be useful for you. Results of genetic testing may give your doctor information that changes your medical care. Changes in the NOD2/CARD15 gene have been related to types of Crohn disease that:

  • Starts at a younger age
  • Affects the ileum, which is the lower part of the small intestine, just before it joins the large intestine
  • Is more likely to cause a narrowing or blockage of the GI tract. This may make you need surgery more often.

If you have genetic testing and one or more gene changes are found, your doctor may want to treat your symptoms more aggressively. This may mean a different choice of medicine or an earlier surgery.

If you have genetic testing and no gene changes are found, your doctor will continue to treat you based on your symptoms.

Before making a decision about Crohn disease genetic testing, you should consider the benefits, limitations, and possible uses for you. Learn more about the pros and cons of genetic testing for Chron disease.

You told us that you've had testing for Crohn disease that hasn't given you a clear answer. Genetic testing may be useful. Crohn disease and another, related condition called ulcerative colitis are both inflammatory bowel disease (IBD). This means that they can share some features. While other testing can often tell them apart, sometimes it is hard to tell one from the other. People who fall in this uncertain category are sometimes told they have "indeterminate colitis."

  • If you have genetic testing for Crohn disease and a gene change is found, it may "tip the scale" in favor of a diagnosis of Crohn disease.
  • If you have genetic testing for Crohn disease and a gene change is not found, these results probably won't be helpful. Only about 50% of people with Crohn disease have these gene changes, so you can have Crohn disease even if your test results don't find a gene change. Your doctor will continue to treat you based on your symptoms.

Before making a decision about Crohn disease genetic testing, you should consider the benefits, limitations, and possible uses for you. Learn more about the pros and cons of genetic testing for Chron disease.

You told us that you have a higher risk of Crohn disease because of your family history or ethnic group, but you don't have Crohn disease or any symptoms of it. Genetic testing is not likely to be useful for you.

At this time, genetic testing for Crohn disease is used to help confirm a diagnosis of Crohn disease, or to help make treatment decisions. It does not provide useful information for people who are only at risk for the condition. Even if you have a gene change associated with Crohn disease, there is no way to predict whether you'll get it. There isn't anything you can do to prevent it, either.

You can learn about the common symptoms of Crohn disease by reading What Is Crohn Disease?. If you develop any of them, you should see a doctor.

You told us that you are worried about getting Crohn disease even though you don't have any symptoms or risk factors for it. While genetic testing is technically possible for you, it generally isn't recommended. If your results are normal, it doesn't rule out the chance that you could get Crohn disease. If the results find a gene change, there is no way to predict whether you'll get it. There isn't anything you can do to prevent it, either.

You may wish to talk to a doctor who can address your concerns and answer your questions.