Diagnosis depends on findings from muscle biopsy, electromyography, ischemic forearm testing, creatine kinase testing, patient history, and physical examination.  Biochemical
Diagnosis depends on patient history and physical examination, muscle biopsy, electromyelography, ischemic forearm test, and creatine kinase level.
In some cases, liver transplantation may abolish biochemical abnormalities. Active research continues.