Genetic testing for HD

Genetic testing for HD has been available since 1993. Genetic testing is done in a special laboratory. It involves the examination of your DNA extracted from a blood sample.
There are two types of genetic testing:

• Diagnostic testing - to confirm a diagnosis of HD in people with symptoms of the disease
• Predictive testing- where a person with a family history of HD, wishes to know whether or not they have inherited the abnormal HD gene, even though they are currently have no symptoms.

Choosing to have a predictive test is a very personal decision. Huntington’s Victoria provides information to people who are at risk and want to consider the pros & cons of testing before making contact with the Testing Service.

Many people ‘at risk’ choose not the take the test. One reason may be that there is still no treatment to prevent HD from developing if the gene is present. But some people want to know whether they will eventually get the disease, so they can make arrangements as far as careers, insurance, family planning, and other issues are concerned.

In Victoria, testing is available through Genetic Health Services Victoria, which is located at the Royal Children's Hospital. Costs are covered by Medicare. Testing is generally only available to people aged 18 years and over, because of the serious implications of the results. A predictive test coordinator and specialist medical team ensure that the person wishing to take the test receives appropriate information and counselling.

Planning a family

Knowing that you are “at risk” for HD may influence your family planning decisions. You may wish to discuss your options with a genetic counsellor.

Prenatal testing

It is possible to determine if a foetus is carrying the gene for HD. The prenatal procedures currently available are Amniocentesis and Chorionic Villus Sampling (CVS). It is advisable for a couple to discuss prenatal testing options with a genetic counsellor prior to becoming pregnant. If an at-risk partner wishes to be tested for the HD gene, it is recommended that the testing process be completed before conception.

In Vitro Fertilisation (IVF)

Another option open to parents is in vitro fertilisation with pre-implantation screening. In this procedure, embryos are screened to determine which ones carry the faulty HD gene. Embryos which do not have the faulty HD gene are then implanted in the woman's uterus.

Further information

Read our Fact sheet on Predictive Testing

Huntington’s Victoria has a DVD called "Freedom of Choice ". In this DVD a number of people at risk discuss their views and feelings about predictive testing and the decisions that were right for them. Contact us if you would like a free copy at info@huntingtonsvic.org.au.

Genetic Health Services Victoria www.genetichealthvic.net.au, email: mcri@mcri.edu.au or phone:(03) 8341 6201.