One third have mild, nonprogressive intellectual impairment that affects verbal ability more than performance. Becker muscular dystrophy is a less severe variant, also due to a mutation at the Xp21 locus. Dystrophin is reduced in quantity or in molecular weight. Patients usually remain ambulatory, and most survive into their 30s and 40s. Diagnosis and Treatment Diagnosis is based on characteristic clinical findings, age of onset, and family history, supported by evidence from electromyography, muscle biopsy, and dystrophin immunostaining.
Muscle biopsy shows necrosis and variation in muscle fiber size.
Referral to major medical centers specialized in these areas is recommended. No specific treatment exists. However, daily prednisone produces significant, long-term clinical improvement. But because of side effects, prednisone should be reserved for patients with major functional decline. Gene therapy is not yet available.