Genetic Testing and Counseling

• Is there genetic testing available for Hirschsprung disease? 

Yes, genetic testing is available for RET gene--the main gene known to be implicated in Hirschsprung disease.  It is estimated that a genetic change (mutation) will be found in the RET gene in about 15-35% of isolated cases (individuals with no family history), and about 50% of individuals with a family history of Hirschsprung disease. For long segment and total colonic Hirschsprung disease, a mutation will be found in about 70-80% of cases. In short segment disease, the likelihood of finding a mutation is generally lower, about 10-35%.

• Who performs the genetic testing?

There is one commercial laboratory in the US that performs genetic testing of the RET gene. It is called GeneDx (www.genedx.com) and it is located in Gaithersburg, MD.

• How can I get the genetic test?

Due to the complexity of the testing, you should speak with a genetic counselor or doctor to determine if it is right for you.  This person will also discuss the pros and cons of genetic testing, including the possibility of genetic discrimination.

The test must be ordered by your doctor or genetic counselor. The laboratory communicates your results to the person who ordered the test, who would discuss them with you. You may also wish to check with your insurance company before ordering this test to check on coverage.

• What will my results tell me?

(+) If a mutation is found in the RET gene, that helps explain the occurrence of Hirschsprung disease in that individual. It will also mean that any children of that individual are at 50% risk to inherit the mutation.  However, it is important to remember that children who inherit a RET mutation do not always have Hirschsprung disease.  Unfortunately, the type of mutation cannot tell us whether or how severely a person will be affected, but research on this is underway.

(-) If no mutation is found, no further information has been gained.  There could be a mutation in the RET gene that cannot be detected, or there could be a mutation in a totally different gene (or no gene) that is causing Hirschsprung disease.  However, there is no other genetic testing available at this time.

• What is genetic counseling?

Genetic counselors are health professionals with specialized graduate degrees and experience in the areas of medical genetics and counseling.  Genetic counselors provide information and support to families who have members with birth defects or genetic disorders and to families who may be at risk for a variety of inherited conditions. They interpret information about the disorder, analyze inheritance patterns and risks of recurrence and review available options with the family.

• How can a genetic counselor help me?

A genetic counselor can assist a family who has a member with Hirschsprung disease by:

            -advising of the chances for another baby to have it

            -exploring testing options

            -interpreting test results

            -facilitating personal decision-making.

To find a genetic counselor in your area, go to www.nsgc.org and click on “Find a Counselor”.