The diagnosis can be established by muscle biopsy. Investigations The serum creatinine is raised. Differential diagnosis * Acid maltase deficiency * Danon disease
Myopathy, X-linked, with excessive autophagy
Sporadic late-onset nemaline myopathy
Desmin-related myofibrillar myopathy
Variably protease-sensitive prionopathy
Frontotemporal dementia and parkinsonism linked to chromosome 17
Familial encephalopathy with neuroserpin inclusion bodies
Pantothenate kinase-associated neurodegeneration
Hereditary motor and sensory neuropathy with proximal dominance