DMD; Duchenne Syndrome; Dystrophinopathy, Duchenne Type

Duchenne Muscular Dystrophy is a progressive genetic disorder characterized by muscle weakness and wasting, loss of motor skills and ambulation, and, eventually, heart failure and respiratory failure. The Duchenne type is the most common of the muscular dystrophies.

Cardiac complications associated with Duchenne Muscular Dystrophy begin early in life, and include weak or irregular heartbeat. In late adolescence and adulthood, the heart enlarges, causing symptoms to worsen. This condition, called dilated cardiomyopathy, is a leading cause of death in Duchenne Muscular Dystrophy patients.

Duchenne Muscular Dystrophy is caused by a mutation on the DMD gene. The mutation prevents the production of dystrophin, a protein critical to the health and growth of muscle cells. The condition follows an x-linked recessive inheritance pattern and almost exclusively affects males.

Diagnostic testing: Genetic testing for the specific mutation in the DMD gene that causes Duchenne Muscular Dystrophy is necessary to confirm the diagnosis. A milder condition known as Becker Muscular Dystrophy is associated with a different mutation in the same gene.

Physical findings: Physical symptoms include:

• •

  Dyspraxia (deficit in motor control);

• •

  Abnormal gait;

• •

  Progressive inability to stand and walk;

• •

  Joint contracture (painful stiffness);

• •

  Scoliosis;

• •

  Cognitive and intellectual impairment;

• •

  Behavioral and mood disorders,

ICD-9: 359.1

ICD-10:G71.01

Although onset of Duchenne Muscular Dystrophy occurs in early childhood, progression of symptoms through juvenile and adolescent ages is unpredictable and can be slowed to some degree with medication.

Nearly all males diagnosed with Duchenne will require the use of a wheelchair by attainment of age 18, and complications from cardiomyopathy and respiratory issues typically lead to death before the age of 30.

There is no cure for Duchenne Muscular Dystrophy. Treatment is symptom-specific and supportive. Corticosteroids have been shown to somewhat slow progression of muscle wasting during childhood and adolescence. Breathing assist devices can prolong life in later-stage patients with respiratory problems.

Suggested MER for Evaluation:

• •

  Clinical history and examination that describes the diagnostic features of the impairment;

• •

  Positive multiplex-ligation dependent probe amplification (MLPA) genetic test for large deletion/duplication mutations on the DMD gene, and microdeletion/microduplication mutations if necessary;

• •

  Muscle biopsy;

• •

  Family history to identify related female carriers; and

• •

  Treatment records including surgical procedures and progress notes.

Suggested Listings for Evaluation:

REMARKS

Although Duchenne Muscular Dystrophy is typically diagnosed early in life, claimants under age 18 are significantly less likely to exhibit listing-level impairment.

Criteria for evaluating child claims involving Duchenne Muscular Dystrophy are provided in 111.13.