How genetic mutations cause Duchenne muscular dystrophy (DMD)
Approximately one-third of DMD cases are thought to arise because of de novo mutations, with the remaining two-thirds of cases inheriting the mutation from carrier mothers.1,2
How is DMD inherited?
DMD is inherited in an X-linked recessive pattern. Since males have only one X chromosome, a mutation in the gene responsible for DMD is sufficient to cause the condition.4
Females have two X chromosomes, so a mutation would have to occur in both copies of the gene responsible for DMD to cause the disorder.4
In X-linked recessive inheritance, a female with one mutated copy of the gene can pass it on to her children. Every son and daughter of a female carrier has a 50% chance of inheriting the faulty gene. Sons who inherit the faulty gene will have DMD, while daughters will be carriers.4
DID YOU KNOW: Duchenne muscular dystrophy is inherited in an X-linked recessive pattern4
Carriers of Duchenne muscular dystrophy (DMD): symptoms & care
Approximately 10% of female carriers show some disease manifestations,1,2 which include:
Muscle weakness3-5
Cardiomyopathy3,4
Central nervous system manifestations4
Adapted from references 3-5
The 2018 Duchenne Care Considerations recommend performing cardiac assessment in all female carriers in early adulthood every 3–5 years.3 This should consist of an electrocardiogram and non-invasive imaging. Assessments should be more frequent in those who are symptomatic or imaging-positive.3
Diagnosis of DMD in children takes an average of 2 years from parental concern. Therefore, carrier women may have more children without realising that they carry a DMD mutation.6-8
Carriers may be at risk of Duchenne muscular dystrophy symptoms.3 Learn about the importance of carrier screening for Duchenne muscular dystrophy here.