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What is mitochondrial disease?
Mitochondrial disease is a group of conditions that affect the mitochondria, the tiny structures in your cells that produce energy. When they do not work properly, the body may struggle to keep up with everyday energy needs.
The symptoms can vary a lot from one person to another. Some people are affected mildly, while others have more serious problems that affect several parts of the body.
Common symptoms
One of the most common symptoms is tiredness or low stamina. People may feel exhausted after small amounts of activity, or need much longer to recover after exercise.
Muscle weakness and pain are also common. Some people notice cramps, poor balance, or difficulty climbing stairs and carrying out physical tasks.
Another frequent symptom is exercise intolerance. This means physical activity may cause unusual breathlessness, weakness, or a “burning” feeling in the muscles much sooner than expected.
Symptoms can affect different parts of the body
Mitochondrial disease can affect the brain and nerves as well as the muscles. This may lead to headaches, learning difficulties, delayed development in children, or problems with memory and concentration.
Some people have eye or hearing symptoms. These can include drooping eyelids, double vision, reduced sight, or hearing loss that may come on gradually.
The digestive system may also be affected. Symptoms can include nausea, vomiting, constipation, diarrhoea, abdominal pain, or difficulty swallowing.
Other possible symptoms
Heart problems can happen in some cases, such as an irregular heartbeat or heart muscle weakness. Breathing difficulties may also occur, especially during illness or physical effort.
People may also experience growth problems, diabetes, or hormone-related issues. In children, signs can include poor weight gain, feeding difficulties, or slower development than expected.
Symptoms often come and go, and may worsen during infections, fever, or stress. Because mitochondrial disease can mimic many other conditions, it is not always easy to recognise at first.
When to seek medical advice
If you or your child has a combination of unexplained symptoms affecting energy, muscles, vision, hearing, or development, speak to a GP. They can assess the symptoms and decide whether further tests or a specialist referral are needed.
Seek urgent help if there is sudden weakness, breathing difficulty, chest pain, seizures, or a severe change in alertness. These may need immediate medical attention, whether or not mitochondrial disease has already been diagnosed.
Frequently Asked Questions
Common mitochondrial disease symptoms include muscle weakness, fatigue, exercise intolerance, developmental delay, poor growth, seizures, hearing loss, vision problems, headaches, and problems affecting the heart, brain, or digestive system.
Mitochondrial disease symptoms often cause low energy because cells cannot produce energy efficiently. This can lead to tiredness, weakness, slower movement, difficulty with routine activities, and symptoms that worsen after activity or illness.
Muscle-related mitochondrial disease symptoms can include weakness, cramps, pain, drooping eyelids, poor coordination, reduced stamina, and trouble climbing stairs, lifting objects, or keeping up with physical activity.
Neurological mitochondrial disease symptoms may include seizures, migraines, developmental regression, learning problems, balance issues, movement disorders, stroke-like episodes, and changes in alertness or thinking.
Eye and vision mitochondrial disease symptoms can include drooping eyelids, eye movement problems, reduced vision, light sensitivity, optic nerve damage, and difficulty focusing or tracking objects.
Hearing-related mitochondrial disease symptoms often include progressive hearing loss, difficulty understanding speech, ringing in the ears, and trouble hearing in noisy environments.
Digestive mitochondrial disease symptoms can include poor appetite, vomiting, constipation, diarrhea, abdominal pain, swallowing difficulties, reflux, and slow gut movement.
Heart-related mitochondrial disease symptoms may include irregular heartbeat, chest pain, shortness of breath, fainting, reduced exercise tolerance, and signs of cardiomyopathy such as swelling or fatigue.
Early mitochondrial disease symptoms in infants can include feeding problems, low muscle tone, poor weight gain, delayed development, unusual sleepiness, vomiting, and episodes of breathing difficulty.
Mitochondrial disease symptoms in adults can look like chronic fatigue syndrome, fibromyalgia, migraine disorders, neuropathy, diabetes, thyroid problems, or unexplained muscle weakness and exercise intolerance.
Mitochondrial disease symptoms vary widely because different organs may be affected and severity can differ. One person may mainly have fatigue and muscle weakness, while another may have seizures, vision loss, or heart problems.
Yes, mitochondrial disease symptoms often worsen during infections, fever, surgery, fasting, or major stress because the body needs more energy and mitochondria may not keep up.
Yes, mitochondrial disease symptoms can fluctuate. Many people have good days and bad days, and symptoms may increase after exertion, sleep loss, illness, or prolonged stress.
Metabolic mitochondrial disease symptoms can include lactic acidosis, poor growth, vomiting, low blood sugar, exercise intolerance, and episodes of extreme weakness or illness after fasting or exertion.
Sleep-related mitochondrial disease symptoms can include excessive sleepiness, poor sleep quality, trouble staying asleep, sleep apnea, and fatigue that does not improve with rest.
Breathing-related mitochondrial disease symptoms can include shortness of breath, shallow breathing, reduced exercise tolerance, weak respiratory muscles, and, in severe cases, breathing failure during illness.
Developmental mitochondrial disease symptoms may include delayed sitting, walking, or talking; learning difficulties; poor coordination; regression of skills; and behavioral or attention problems.
Mitochondrial disease symptoms need urgent medical attention if there is sudden weakness, seizures, trouble breathing, fainting, severe confusion, stroke-like symptoms, or rapid worsening after illness.
Doctors evaluate mitochondrial disease symptoms with a medical history, physical exam, blood and urine tests, imaging, heart and hearing tests, eye exams, genetic testing, and sometimes a muscle biopsy.
Yes, mitochondrial disease symptoms can overlap with other genetic or metabolic disorders because many conditions can affect the same organs and produce similar fatigue, weakness, developmental, or neurological problems.
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