Duchenne Muscular Dystrophy is one of the most common inherited disorders worldwide. It is a disorder that affects boys almost exclusively. Parents may first see that their three-to-five year old child has frequent falls, runs slowly, has a toe walking or waddling gait. The child's calves are often unusually large. Weakness is initially most pronounced in the hips and upper leg muscles, but will include most voluntary muscles over time, including those responsible for respiration. The heart similarly becomes weak over time. Weakness of the heart and respiratory muscles make this a fatal disorder that requires careful medical management.
Diagnosis is based on the history of disease, including a possible family history, clinical features found during examination as well as supporting laboratory data. DMD is caused by the absence of a muscle protein called dystrophin. Approximately two thirds of boys with DMD have a large deletion or duplication in the gene for dystrophin that causes their symptoms. These mutations can be detected by a genetic blood test. Our MDA genetics counselor will carefully review the history of disease with each family, discuss the principles of inheritance and help weigh risks and benefits of genetic testing of various family members, including for the patient and potentially carrier testing for the mother. For the remaining one third of boys with clinical characteristics suggestive of DMD but without one of the common, large mutations, a muscle biopsy is often recommended. From the muscle biopsy, it can be determined if there is an absence of dystrophin.
The treatment of DMD requires active participation from health care providers, parents and schools to ensure that each child thrives. Most children with DMD are placed on corticosteroids, which have been shown in clinical trials to decrease the rate of decline of strength. A neurologist on our team will manage this treatment and minimize side effects of the drug. The neurologist also directs and coordinates care among a variety of services. Physical and occupational rehabilitation play a large role in designing exercise programs and teaching stretching activities to minimize limiting contractures. Severe contractures and scoliosis are treated by orthopedic surgeons on our team who have significant experience with DMD. Heart function is followed by EKG and echocardiograms reviewed by pediatric cardiologists. Our Muscular Dystrophy Association liaison is actively involved with families and schools to offer support on a number of levels including social, financial and educational.
The Muscular Dystrophy Center at Johns Hopkins is designed to maximize independent function and minimize complications of DMD. We welcome the opportunity to work with families living with DMD.