How is DMD inherited?
Duchenne muscular dystrophy (DMD) is caused by an altered gene found on the X-chromosome, so the condition usually affects only boys. In some cases, the disorder appears 'out of the blue', following a new mutation in the unfertilised egg. In others, DMD is inherited from a carrier mother, who is usually unaffected herself. A carrier mother has a one-in-four chance of having an affected son and a one-in-four chance of having a carrier daughter.