Diagnosis and Treatments
What Are the Treatments?
Currently there are no highly effective mitochondrial disease treatments. Though related symptoms, such as seizures or attention problems can be managed with various medications, the mitochondrial disease itself is unchanged. Unfortunately, supplements such as CoQ10 and L-Carnitine have little to no effect on most patients.
In 2009, FDA approval occurred for an EID (Emergency Intervention Drug) to treat a mitochondrial disease with the new drug from Edison Pharmaceuticals, EPI-743. This represents the first steps toward viable treatments and hopefully, the beginning of many more near-term advancements in mitochondrial medicine research.
How Are Mitochondrial Diseases Diagnosed?
There is no single test to diagnose mitochondrial disease in most patients. Today, OXPHOS (oxidative phosphorylation) enzymology by itself is no longer sufficient for a diagnosis. OXPHOS is the process by which the mitochondria turn the food we eat into energy that can be used by key organs; in the same way that crude oil can’t go directly into a car to make the engine run, it first needs to be refined and turned into gasoline. The mitochondria represent the most complicated enzyme system in the body, requiring over 1,000 genes to function properly. As you might guess, with so many genes, patients can present in hundreds of ways.
Diagnosis of mitochondrial disease can be made through a combination of clinical observations, laboratory evaluation, brain imaging, and muscle biopsies. And an experienced integrated approach is necessary – not just one test. Referral to a specialist in mitochondrial medicine is often needed for diagnosis. Rarely is genetic testing sufficient for the diagnosis of mitochondrial disease. Even with the advent of new gene sequencing techniques like Next Generation sequencing, many of the identified changes in genes require the information obtained from a muscle biopsy for interpretation.
What Is Needed for Diagnosis?
In order to apply diagnostic criteria patients need testing that specifically assesses the different mechanisms causing the abnormalities (the how and the why) associated with OXPHOS defects. This understanding has evolved significantly in the past five years. And because of the complexity of the disease, continued thinking, assessing and investigating are terribly important to diagnosis accuracy. Due to the rapid changes in our understanding of mitochondrial diseases and the tools available for diagnosis, physicians need to reassess the probability of a diagnosis of mitochondrial disease as they see the patients over time. The diagnosis may change.
Most importantly, when a diagnosis of mitochondrial disease or disorder is considered, patients need to be evaluated carefully for diseases other than mitochondrial disease. For example, the muscle biopsy can be used to look at other types of muscle diseases. When a mitochondrial disease evaluation is undertaken, the physician should approach the patient comprehensively with assessments for mitochondrial diseases and other categories of disease.
It is critical for patients and their families not to oversimplify the diagnosis. In most cases, calling a patient simply a “Complex I disease” or a “Complex I and Complex III disease” is an oversimplification. By carefully understanding the complexities of patients with mitochondrial disease or disorders, the probability of an accurate diagnosis can be increased and better clinical trials can be constructed.
What Are the Tests for Mitochondrial Disease?
There are three Categories of Diagnostic Criteria: Clinical, Biochemical and Genetic. Think of it as a very long restaurant menu but, instead of selecting one from column A and one from column B, physicians involve multiple tests from these three broader categories.
Once these tests have been performed, experienced physicians diagnose according to specific criteria categorization:
Unlikely: Criteria– 1-7 tests are normal
Possible: Criteria– a single test is abnormal and the other tests are normal or equivocal
Probable: Criteria–two tests are abnormal
Highly Probable: greater than two tests are abnormal