Why genetic confirmation is important

Genetic counselling and carrier testing

  • Sometimes the genetic mutation causing DMD arises by chance in the boy. This is considered a spontaneous mutation. In other cases, it has been passed on by the boy’s mother.
  • If the mother has the mutation, she is called a “carrier”, and she can pass the genetic mutation on to her other children. The boys she passes it on to will be affected by DMD, while the girls will be carriers themselves. If the mother is tested and is found to have the mutation, she can make informed decisions about future pregnancies, and her female relatives (sisters, aunts, daughters) can also be tested to see if they are also at risk of having a boy with DMD.
  • Even when a woman is not a carrier, there is a small risk to future pregnancies because the mutation may occur in her ova or egg cells. This is called “germ line mosaicism”.
  • A carrier also has a small risk of developing a weak heart or even leg weakness later in life. Knowing carrier status helps to identify this risk so the woman can get proper advice.
  • You should have access to a genetic counsellor who can explain all this to you in more detail.

Eligibility for clinical trials

There are a number of clinical trials underway in DMD that are targeted to certain types of mutations. Genetic testing is important to understand whether your boy is eligible to participate in these trials. To help doctors find the boys who might be eligible, you should register in a patient registry.

The most important question you need to have answered is whether the genetic testing performed was up to currently accepted standards, allowing the exact mutation to be defined. If it was not, then further testing might be required. You should discuss this with your doctor. The exact mutation is also needed to register with one of the DMD registries. You can find details of the kinds of tests that might be done and how effective they are at detecting the absolute detail of the mutation in the main document.

All of the national patient registries for DMD across the world are listed at: www.treat-nmd.eu/patientregistries.

Please see this website for more details.

Information based on consensus statement (published in January 2010)