Natural History in Primary Mitochondrial Myopathies

This study follows patients with primary mitochondrial myopathy (PMM) — a group of genetic diseases that damage the mitochondria (the energy factories in cells), causing progressive muscle weakness and exercise intolerance — to understand the natural course of these conditions over time. This is an observational study; no experimental treatments are given. The data collected will help researchers design better future clinical trials. You may be eligible if: - You are 16 years or older - You have muscle symptoms such as exercise intolerance, fatigue, muscle pain, recurrent muscle breakdown (rhabdomyolysis), drooping eyelids (CPEO), or progressive muscle weakness - You have a confirmed primary mitochondrial DNA mutation or a pathogenic mutation in nuclear DNA genes related to mitochondrial maintenance (e.g., TK2, POLG, TWNK, RRM2B) You may NOT be eligible if: - There are no specific exclusion criteria listed for this study Talk to your doctor to see if this trial is right for you.