A 17-year-old boy presents with 2-year history of progressive proximal muscle weakness affecting hip and shoulder girdles. He ambulates independently but reports difficulty rising from chairs. Vital signs: BP 118/76, HR 92, RR 16, Temp 37°C. Cardiac evaluation reveals early dilated cardiomyopathy with ejection fraction 45%. Serum creatine kinase is elevated at 2,800 U/L. Muscle biopsy shows reduced but not absent dystrophin expression. Cognitive function remains normal. Which diagnosis best explains these findings?
- A)Mitochondrial myopathy
- B)Becker muscular dystrophyGABARITO
- C)Duchenne muscular dystrophy
- D)Polymyositis
- E)Guillain-Barré syndrome
Explicação
Becker muscular dystrophy is caused by a nonframeshift mutation leading to reduced or abnormal dystrophin. Compared with Duchenne muscular dystrophy, onset is later and progression is slower, though cardiomyopathy is still common. Ver explicação completa e trilha adaptativa →