The parts of the body that need the most energy, such as the heart, brain, muscles and lungs, are the most affected by mitochondrial disease. The affected individual may have strokes, seizures, gastro-intestinal problems, (reflux, severe vomiting, constipation, diarrhoea), swallowing difficulties, failure to thrive, blindness, deafness, heart and kidney problems, muscle failure, heat/cold intolerance, diabetes, lactic acidosis, immune system problems and liver disease.
A tough question to answer because the prognosis depends upon the severity of the disease and other criteria. As more research dollars are raised to find more effective treatments and ultimately a cure, some of the affected children and adults are living fairly normal lives with mitochondrial disease. In other cases, children may not be able to see, hear, talk or walk. Affected children may not survive beyond their teenage years. Adult-onset can result in drastic changes from an active lifestyle to a debilitating illness is a short amount of time.
The child or adult may have seizures, severe vomiting, failure to thrive, heat/cold intolerance, poor muscle tone, delayed achievement of milestones, severe diarrhoea/constipation, feeding problems, unable to fight typical childhood infections or repeated infections and fevers without a known origin. A “red flag” for mitochondrial disease is when a child or adult has more than three organ systems with problems or when a “typical” disease exhibits atypical qualities.
The child or adult is at highest risk for neurological and organ damage during and for the two weeks following an illness. Therefore, even a simple flu or cold virus can have devastating effects on the patient, even death. Any illness must be treated immediately with medical interventions, like IV fluids and IV antibiotics.
Yes, many adults are diagnosed with adult-onset mitochondrial disease. Some of these individuals have been ill their whole lives but went undiagnosed. Others have carried the genetic mutation that causes mitochondrial disease since birth but did not show any symptoms until a severe illness brought them on. Adult mitochondrial patients are affected in a similar manner to the children who are affected.
There is no single test to diagnose mitochondrial disease in most patients. There are varying degrees of manifestation of symptoms so, along with your primary care physician a specialist can evaluate the appropriate next steps in diagnosis.