Expert Opinion :
This child has proximal muscle weakness with pseudo-hypertrophy of calf muscles, onset at 9 years of age and normal sisters. Thus the diagnosis is Becker’s muscular dystrophy. Diagnosis of BMD is based on clinical grounds and laboratory investigations
Clinical features include:
• Proximal muscle weakness
• Positive Gower’s sign
• Pseudo-hypertrophy of calf muscles
• Delayed motor milestones
• Onset usually in later part of first decade of life
• Dilated cardiomyopathy (in 2nd- 3rd decade of life)
Laboratory features include:
• Elevated Serum creatine kinase (i.e., 5-100 times normal).
• Muscle biopsy with dystrophin antibody staining demonstrates the presence of dystrophin in variable percentages.
• Polymerase chain reaction (PCR), southern blots analysis, or fluorescent in situ hybridization demonstrates Dystrophin gene deletion in about 98% of cases.
• EMG: normal nerve conduction with possible borderline-to-low motor evoked responses