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What is mitochondrial disease?
Mitochondrial disease is a group of rare conditions that affect the body’s energy supply. Mitochondria are the parts of cells that help turn food into energy. When they do not work properly, different organs and tissues can be affected.
The symptoms can vary a lot from person to person. Some people are affected from birth or early childhood, while others develop problems later in life. Because many organs need energy, the signs may involve several parts of the body at once.
Common symptoms
One of the most common symptoms is tiredness or low energy that does not improve with rest. People may feel weak, struggle with exercise, or find everyday tasks much harder than expected. Muscle pain and cramps can also happen.
Another common sign is delayed development in children. This may include slower learning to sit, walk or talk, as well as poor growth or difficulty gaining weight. Some children also have low muscle tone, meaning they feel floppy or less strong than expected.
Problems with balance and coordination are also possible. A person may seem unsteady when walking, fall more often, or have difficulty using their hands for tasks that need precision. Tremor and involuntary muscle movements can occur in some cases.
Symptoms affecting the brain and nerves
Mitochondrial disease can affect the brain and nervous system. This may lead to seizures, headaches, developmental regression, or difficulty concentrating. Some people experience strokes or stroke-like episodes, which can cause sudden weakness, confusion or loss of speech.
Vision and hearing problems are also common. This may include reduced eyesight, droopy eyelids, double vision, or hearing loss. These symptoms can appear gradually or worsen over time.
Symptoms affecting the heart, digestion and other organs
Some people develop heart problems, such as an abnormal heartbeat or weakness of the heart muscle. This can cause breathlessness, palpitations or tiredness. In more serious cases, it may lead to heart failure.
Digestive symptoms are also seen in many people. These can include tummy pain, vomiting, constipation, diarrhoea, difficulty swallowing, or poor appetite. Liver, kidney and hormone problems may also happen, depending on which organs are affected.
When to seek medical advice
If symptoms seem to affect several parts of the body, or if a child is not meeting developmental milestones, it is worth speaking to a GP. Ongoing fatigue, muscle weakness, seizures, hearing loss or vision changes should also be checked. These symptoms do not always mean mitochondrial disease, but they should not be ignored.
Diagnosis can take time because the symptoms overlap with many other conditions. A specialist may recommend blood tests, scans, genetic testing or a muscle biopsy. Early assessment can help families get the right support and treatment.
Frequently Asked Questions
Common mitochondrial disease symptoms can include muscle weakness, exercise intolerance, fatigue, seizures, vision or hearing problems, developmental delay, migraines, and issues affecting the heart, liver, or nerves.
Early mitochondrial disease symptoms in children may include poor growth, delayed development, low muscle tone, feeding problems, fatigue, repeated vomiting, seizures, and trouble keeping up with physical activity.
Yes. Mitochondrial disease symptoms in adults may present as fatigue, muscle pain, exercise intolerance, neuropathy, hearing loss, diabetes, heart rhythm problems, migraines, or gradual weakness.
No. While muscle weakness and exercise intolerance are common mitochondrial disease symptoms, the condition can also affect the brain, eyes, ears, heart, liver, kidneys, and endocrine system.
Yes. Persistent fatigue and low energy are very common mitochondrial disease symptoms because cells may not produce enough energy to support normal activity.
Yes. Neurological mitochondrial disease symptoms may include seizures, developmental delay, learning difficulties, headaches, stroke-like episodes, neuropathy, balance problems, or changes in movement.
Yes. Vision-related mitochondrial disease symptoms can include drooping eyelids, eye movement problems, blurred vision, optic nerve damage, or progressive vision loss.
Yes. Hearing loss is one of the possible mitochondrial disease symptoms and may be gradual or sudden, sometimes occurring along with balance problems or tinnitus.
Yes. Digestive mitochondrial disease symptoms can include poor appetite, vomiting, constipation, diarrhea, swallowing difficulty, abdominal pain, and trouble maintaining weight.
Yes. Cardiac mitochondrial disease symptoms may include cardiomyopathy, irregular heart rhythms, chest discomfort, shortness of breath, fainting, or reduced exercise tolerance.
Yes. Breathing-related mitochondrial disease symptoms can occur when respiratory muscles are affected or when there is poor energy production, leading to shortness of breath or weak breathing.
Yes. Exercise intolerance is a hallmark of many mitochondrial disease symptoms, and physical activity may trigger worsening weakness, pain, exhaustion, or muscle cramps.
No. Mitochondrial disease symptoms can range from mild to severe and may affect one organ system or many. Symptoms can also change over time.
Mitochondrial disease symptoms often develop gradually, but they may seem sudden during illness, stress, fasting, or increased physical demand when the body needs more energy.
Mitochondrial disease symptoms are diagnosed through a combination of medical history, physical examination, blood and urine tests, imaging, genetic testing, muscle studies, and evaluations of affected organs.
Yes. Mitochondrial disease symptoms can overlap with many other disorders, including neuromuscular diseases, epilepsy, chronic fatigue conditions, metabolic disorders, and autoimmune diseases.
Common triggers for worsening mitochondrial disease symptoms include infections, fever, fasting, dehydration, stress, poor sleep, strenuous exercise, and some medications.
Yes. In children, mitochondrial disease symptoms may include poor growth, delayed milestones, learning problems, and developmental regression, depending on which tissues are affected.
Medical help should be sought for mitochondrial disease symptoms such as new seizures, fainting, breathing trouble, stroke-like episodes, worsening weakness, heart symptoms, or sudden vision or hearing changes.
Yes. Although there is no cure for many forms of mitochondrial disease, mitochondrial disease symptoms can often be managed with supportive care, symptom-specific treatments, nutrition planning, exercise guidance, and regular specialist follow-up.
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