Since there is a wide range of clinical symptoms caused by mitochondrial dysfunction, no one of which is specific for any known mitochondrial disease, the diagnosis of a mitochondrial disease can be a challenge. Genetic testing can sometimes identify a change in a person’s DNA that can be used to confirm the diagnosis of a mitochondrial disease. In many (or most) cases, however, a mitochondrial disorder may be suspected, but cannot be definitely confirmed by testing.
Some tests that may be done to determine the likelihood of a mitochondrial condition include:
- Blood tests
- Urine tests
- Muscle biopsy (a small piece of the muscle is removed and examined under a microscope)
- Brain MRI (pictures of the brain)
- EEG (test to evaluate for seizures)
- EKG and echocardiogram (tests to check for heart problems)
- Audiology evaluation (for problems with hearing)
- Ophthalmology examination (to evaluate vision)
- Obtaining a pedigree (collecting the patient’s medical and family history)
- Genetic testing (on a blood sample and/or muscle biopsy)
Testing is usually individualized for each patient, and is often focused on the specific set of symptoms and body regions involved. Once testing is complete, however, a specific diagnosis of a mitochondrial disease may still not be possible. Although this can be frustrating for the patient and family, the systematic and broad-based work-up outlined above will identify the known mitochondrial diseases, and will eliminate from consideration many conditions that can confuse the diagnosis and interfere with proper treatment.