Dystrophinopathies: Molecular Genetic Testing

TREATMENT

Goals of therapy in DMD/BMD are to maintain function, prevent contractures, and provide psychologic support. Physical therapy utilizes passive stretching exercises to prevent contractures of the iliotibial band, the Achilles tendons, and flexors of the hip; contractures may be addressed through orthopedic surgery and bracing. Standing and/or walking, which seem to prevent scoliosis, can be maintained by using long-leg braces. A cardiac evaluation is recommended upon diagnosis or by the age of 6 years. Annual pulmonary function studies, electrocardiography, and echocardiography should be performed after the age of 10 years. Symptomatic nocturnal hypoventilation may be treated with overnight mouth intermittent positive pressure. Respiratory assistance may be advisable during periods of respiratory infection.

Medications for Duchenne Muscular Dystrophy. Clinical studies demonstrate that prednisone improves the strength and function of patients with DMD. Deflazacort, a synthetic derivative of prednisolone, has been suggested to have fewer side effects than prednisone, particularly regarding weight gain. Deflazacort is used in Europe and Canada but is unavailable in the United States.

Practice parameters for the use of corticosteroid therapy have been published by the American Academy of Neurology and the Child Neurology Society. Some of the following recommendations are in accordance with those parameters.

• Boys with DMD, who are older than 5 years, may be treated with prednisone (0.75 mg/kg/day). Patient and family need to be made aware of potential benefits and risks of corticosteroid therapy before initiating therapy.

• Assess the potential benefits of corticosteroid therapy.

• Continue optimal maintenance dose of prednisone (0.75 mg/kg/day) if side effects are not severe. Improvement may remain significant but less robust with gradual tapering (as low as 0.4 mg/kg/day).

• Deflazacort (0.9 mg/kg/day) may be used to treat DMD with careful monitoring of side effects (weight gain, asymptomatic cataracts).

Therapies under Investigation. Experimental gene therapies as well as ribosomal read-through and exon skipping are currently under investigation. Stem cell therapy is under investigation but remains experimental. Myoblast transfer has been inefficient.

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