A new study published in the Journal of Neurology suggests that despite long-held beliefs that female carriers of Duchenne muscular dystrophy (DMD) mutations are generally unaffected, some do experience symptoms.
DMD is caused by a defect of the DMD gene of the X chromosome, and primarily affects males. While boys are born with one X chromosome, girls have two, so if a female has a DMD mutation, there’s usually a healthy copy of the gene to compensate. As such, the medical community has traditionally viewed them as “asymptomatic carriers,” but a growing body of research has demonstrated that women can indeed develop symptoms and complications.
Learn more about DMD treatment and care
The study included 47 female participants heterozygous for DMD mutations, meaning they had one X chromosome with the mutation and one with a healthy copy of the gene. Fifty-seven percent were asymptomatic, while 43% exhibited symptoms. The researchers ran a number of tests, including muscle strength assessments, cardiac examinations, creatine kinase (CK) level measurements, muscle biopsies and genetic testing.
The results revealed that among the symptomatic subjects, muscle weakness predominantly occurred in the legs and arms, similar to how DMD manifests in male patients. Twenty percent of participants had cardiac involvement, with dilated cardiomyopathy being the most common heart issue.
One out of the nine cardiomyopathy patients did not exhibit any muscle weakness. “Hence, it is crucial to increase awareness of a possible cardiomyopathy in DMD carriers, even if asymptomatic,” the study’s authors wrote.
Furthermore, CK level testing — a common blood test for muscle damage — did not always detect DMD-related issues. Some symptomatic women had normal CK levels, suggesting other evaluations may be necessary to make a DMD diagnosis.
The study’s authors concluded that healthcare providers should be aware that women with DMD mutations can have significant muscular symptoms and heart issues, and regular cardiac evaluations are essential for early detection and management. They also noted that more research and a better understanding of DMD mutations in heterozygous females are needed to develop new therapies for the disease.
Sign up here to get the latest news, perspectives, and information about DMD sent directly to your inbox. Registration is free and only takes a minute.
