Carriers of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked disease, which means that the gene causing the disorder is located on the X chromosome.¹ Girls have two X chromosomes and boys have only one. This means that almost all affected individuals with DMD are male, while females can be carriers. A genetic carrier is someone who has inherited the faulty gene that causes a certain disorder but does not necessarily show symptoms.²

Normally, DMD carriers do not show symptoms. This is because, if a girl inherits the faulty dystrophin gene, she has a ‘back-up’ healthy copy of the dystrophin gene on her other X chromosome, which usually compensates for the faulty one and produces enough of the dystrophin protein.²

However, sometimes a carrier is unable to produce enough dystrophin. This means that they will experience some signs and symptoms of DMD, which can be treated in the same way as boys with the condition.²

DMD may affect future pregnancies

If a woman is a DMD carrier, she may have another baby with DMD.²

The chances of a carrier having a child with DMD are 1 in 4 (or 25%). This means that for every baby she has, there is a 1 in 4 chance that the child will have DMD.²

In all carriers, regular strength check-ups and close heart monitoring are important to make sure that any symptoms that may arise are properly treated.² This is why it is so important for female relatives of a boy with DMD to get tested to find out whether or not they are carriers.