Muscular dystrophy and genetic testing

You may want to consider genetic testing if you have a family history of muscular dystrophy (MD) and are concerned about passing it on to your unborn children.

Usually, a person develops MD when they inherit a particular faulty gene (gene mutation) from one or both parents. Several types of muscular dystrophy can be identified through genetic testing. Discuss the issue with your GP, who can refer you for appropriate genetic counselling and testing.

Genetic testing can be used to:

• Identify MD carriers.
• Perform a prenatal diagnosis, i.e. test the baby in the womb for MD genes.
• Help diagnose MD, along with other tests and physical examinations.

Identifying MD carriers

Some types of MD are carried without causing the condition, i.e. the carrier doesn’t develop symptoms, but can pass the defective gene on to their child, who then does develop the disease.

A sample of DNA is taken from cells in the blood, saliva or tissue and tested to find out if the person is carrying the faulty gene.

If it’s found that you or your partner are a carrier and at risk of passing MD on to your child, your counsellor will discuss options with you.

Prenatal diagnosis

Prenatal diagnosis involves diagnosing a baby with MD before birth, using tests carried out during pregnancy.

There are two main procedures for this:

• Chorionic villus sampling (CVS): During early pregnancy, a small tissue sample is taken from the placenta, which contains the same DNA as the foetus. The sample is removed by catheter or a fine needle inserted through the cervix or abdomen.
• Amniocentesis: Usually done at 14-16 weeks of pregnancy, a sample of amniotic fluid (which surrounds the foetus in the uterus and contains shed foetal cells) is taken. Under local anaesthesia, the sample is removed with a thin needle inserted through the abdomen into the uterus.

The cells in the sample are tested to determine whether they have the genetic mutation that causes MD, which means the child is likely to develop MD at some point. If this is the case, your genetic counsellor will discuss your options with you.

Note that these tests can sometimes give misleading or unexpected results, so it’s important to discuss possible results with your genetic counsellor or doctor before going ahead with the procedure. Also, the test only looks for the particular type of MD in the family but not for other possible problems.

Sometimes, spontaneous gene mutations occur that can cause MD to develop in people with no family history of the disease.

Source: 

– National Institute of Neurological Disorders and Stroke (NINDS). (2011). Muscular dystrophy: Hope through research.