Question:

I have a question concerning Huntingtons chorea?Is it neccessary to have genetic testing for this desease if a parent has it and you do not wish to pass it on to future children?or can a person with a history of HC become pregnant and have amniocentesis done to determine if the fetus has HC or carries a gene for HC while not knowing thier own HC status.I hope this question makes sense.

Answer:

It is possible. Huntington disease (HD) is an autosomal dominant disorder caused by a mutation or change in a single gene. Anyone who has the gene is affected, and they have a 50% risk or 1 out of 2 chance of passing the gene for HD on to any of their children.

As you may know, Huntington disease is a progressive degenerative brain disorder that usually does not begin to show symptoms until middle to late adulthood. People with Huntington disease usually experience involuntary movements of all body parts – may start as minor twitching, clumsiness and then changes in gait – walking. They also experience cognitive impairment such as changes in judgment and memory. They may also have behavioral or psychiatric problems such as depression. To date, there is no specific treatment or cure for HD.

Prenatal testing for HD is possible for fetuses at 50% risk – that is the parent is known to have the gene. DNA can be taken from fetal cells obtained by amniocentesis or chorionic villus sampling (CVS). Linkage analysis can be used in prenatal diagnosis for a fetus at 25% risk – that is, the parent does not know whether or not they have the gene. However, you would need to know the DNA status of the grandparents in this situation. At most centers, prior testing of family members is usually necessary.

A person`s decision to pursue gene testing is often very complex and a number of issues should be discussed with the family. Thus, genetic counseling is highly recommended. People can contact their doctor or go to the National Society of Genetic Counselors website below to find a genetics center near them.

There is an excellent website that has additional information about HD at the Huntington`s Disease Society of America.

For more information:

The National Society of Genetic Counselors Resource Center
Huntington’s Disease Society of America

Response by:

Anne Matthews, R.N., Ph.D. Director, Genetic Counseling and Family Studies Center for Human Genetics School of Medicine Case Western Reserve University