First, lets get to know what the mitochondria are and what they do. Almost every cell in the human body have tiny organelles called mitochondria, commonly referred to as the “power house” of the cell. There are hundreds sometimes thousands of mitochondria in a single cell. Red blood cells are the only cells that do not contain mitochondria. Mitochondria are responsible for converting the food we eat into a type of energy for the body called ATP. This accounts for 90% of our energy. Therefore, the tissues with high demands for energy, such as muscle, heart, brain, and eye, are particularly vulnerable for mitochondrial defects. Nerves also have a high energy demand .
Mitochondria are the only cellular organelles that contain their own DNA and they are passed from mother to child. MtDNA defects are maternally passed. However, mitochondrial disease can also be sporadic from either environmental toxins or certain medications. Spontaneous mutations can also be the cause of mitochondrial disease. Defects in the nDNA can be inherited from either parent during the fertilization process.
When someone says they have mitochondrial disease, it is really more like someone saying “I have a headache.” That could be a stress, sinus, migraine, etc.. headache. Multiply that analogy by thousands to understand Mitochondrial disease. There are forty specifically named mitochondrial diseases and many more that have yet to receive a name, been applied to text, or have a diagnostic test. The signs and symptoms of vary according to the degree the mitochondria are defected, what mitochondria are affected, and exactly how they are affected. Each specific mitochondrial disease has it's own set of possible and typical symptoms. The severity of the symptoms are also affected by these factors. Symptoms vary from person to person and range from mild to fatal. Even doctors that specialize in mitochondrial diseases are often puzzled by the great diversity in symptoms.
For example: Leigh Disease/Syndrome is a progressive neurometabolic disorder that is fatal. The child often appears normal at birth, but by two years old regresses back to the an infant state of functioning. Symptoms include: loss of basic skills such as sucking, head control, walking and talking, irritability, loss of appetite, vomiting, and seizures. Latter the child develops heart, kidney, vision, and breathing complications. Whereas, Kearns-Sayre Syndrome is a slowly progressive multi-system mitochondrial disease. The symptoms begin with dropping eye lids that progress to paralysis of eye movement, retina degeneration, cardiac conduction defects, elevated cerebrospinal fluid protein, and uncoordinated movements. Death usually occurs by thirty years old. These are just two of the multiple mitochondrial diseases, but you can see how the symptoms vary.
Diagnosis is not an easy task. This is one of the many reasons it is so important to be referred to a specialist. From there, an EEG, brain MRI, metabolic tests (blood/urine/spinal fluid), clinical observations, and muscle biopsy are the usual diagnostic tools. If blood tests, clinical observations, and MRI suggest mitochondrial disease, a muscle biopsy is generally the next step. There is much controversy about fresh vs. frozen muscle biopsies. Some experts say that frozen biopsies are the only reliable way to isolate the mitochondria for analysis. Unfortunately, there are only a handful of facilities in the United States that are capable of performing a fresh muscle biopsy. For one of the mitochondrial diseases, complex V, fresh muscle tissue is the only way it can be analyzed.
At this time, there is not a cure for any of the mitochondrial diseases. All of the treatments are based on diminishing the symptoms and slowing the disease process. Again, effectiveness of treatment is based on which type of mitochondrial disease, etc… Some may improve greatly and notice a decline in symptoms, while treatment in others may be totally ineffective. This can even be said within the same category of mitochondrial disease because each person has a unique biochemical makeup. Also, without isolating which specific mitochondrial disease a child has it can be dangerous to give some of the therapies listed bellow. For example, in electron transport chain disorders a high fat diet is beneficial, but in OXPHOS disorders a high fat diet can be fatal. With that in mind, some of the treatment approaches are: cofactors and vitamins, diet, and multi discipline therapy. Co-Q10, B Vitamins, Vitamin E, and L-Carnitine are some of the common vitamins and cofactors. Avoidance of extreme temperatures, physical therapy, speech therapy, occupational therapy, frequent small meals, and avoiding fasting are common assignments. Diets specifically geared by a metabolic specialist such as: high fat, low fat, low carbohydrate, etc. can be beneficial.
In conclusion, mitochondrial disease is complex with many tiers to it. In recent years it is gaining some recognition in the medical world, but public recognition of this disease has a long way to go. If you say “autism“, most everyone has a general idea of what, why, and how…..but you say “mitochondrial disease” and people cock their head sideways in puzzlement. As the mother of a child with possible mitochondrial disease, I know first hand of this bewilderment. Even most general practicing doctors often ask me “and what is mitochondrial disease?” The lack of reliable conclusive testing is why the “possible” is included when I say my child has mitochondrial disease. All of the clinical symptoms point to mitochondrial disease, but the MRI's, muscle biopsies, etc… have not been able to isolate a specific mitochondrial disease in my daughter. Organizations like UMDF, David P. Campbell Foundation, UCSD's Mitochondrial and Metabolic Disease Center, NORD, and Mitochondrial Disease Action Committeeare making great strides for public awareness, research, cures, and improving diagnostic capabilities.
