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What is mitochondrial disease?
Mitochondrial disease is a group of conditions that affect the mitochondria, the tiny structures in our cells that produce energy. When mitochondria do not work properly, the body may not have enough energy for normal function.
These conditions can affect many parts of the body, especially organs that need a lot of energy. This includes the brain, muscles, heart, eyes and kidneys.
The main cause: genetic changes
Most mitochondrial diseases are caused by genetic changes, also called mutations. These changes affect the instructions the body uses to make proteins needed for energy production.
Some mitochondrial diseases are caused by changes in the DNA found inside the mitochondria itself. This is called mitochondrial DNA, or mtDNA. Other types are caused by changes in genes in the cell nucleus, which contains most of our genetic material.
How the condition is inherited
Mitochondrial disease can run in families. The way it is passed on depends on which gene is affected and whether the change is in mtDNA or nuclear DNA.
mtDNA is usually inherited from the mother. This means a mother can pass a mitochondrial genetic change to her children. Nuclear gene changes can be inherited from one or both parents, depending on the condition.
Spontaneous gene changes
Not all mitochondrial disease is inherited. In some people, the genetic change happens for the first time in them and is not passed down from a parent.
These are known as new, or spontaneous, mutations. They can still cause symptoms, even if there is no family history of the condition.
Why symptoms can vary
People with mitochondrial disease can be affected very differently, even within the same family. This is because cells may contain a mix of normal and faulty mitochondria, and the balance can vary from person to person.
The severity of symptoms often depends on how much the mitochondria are affected and which parts of the body need the most energy. Some people have mild symptoms, while others are more severely affected.
What this means for diagnosis and care
Because mitochondrial disease has many possible causes, diagnosis can be complex. Doctors may use blood tests, genetic testing, muscle tests and other investigations to find the underlying cause.
In the UK, specialist teams may help confirm the diagnosis and plan treatment. While there is no universal cure, understanding the cause can help guide care, monitoring and family advice.
Frequently Asked Questions
Mitochondrial disease causes are usually due to mutations in mitochondrial DNA, mutations in nuclear genes that affect mitochondria, or new spontaneous genetic changes. These defects disrupt how cells produce energy, especially in organs with high energy demands.
Mitochondrial disease causes can be inherited from a parent or arise spontaneously. Some are passed through maternal mitochondrial DNA, while others result from autosomal or X-linked nuclear gene changes or de novo mutations.
Mitochondrial DNA mutations are a major cause of mitochondrial disease causes because they can impair the proteins needed for energy production. Since mitochondria help generate ATP, even small defects can affect muscles, the brain, heart, and other organs.
Nuclear gene mutations contribute to mitochondrial disease causes by disrupting proteins that build, maintain, or regulate mitochondria. These mutations can affect mitochondrial DNA replication, protein assembly, and energy production pathways.
Mitochondrial disease causes often affect organs with the highest energy needs, such as the brain, heart, muscles, liver, and kidneys. These tissues are more vulnerable when mitochondria cannot produce enough energy.
Yes, some mitochondrial disease causes are passed from mother to child through mitochondrial DNA. Because mitochondria are usually inherited from the egg, maternal transmission is common for mitochondrial DNA-related conditions.
Yes, both parents can contribute to mitochondrial disease causes when the problem is in nuclear DNA. Nuclear gene mutations can be inherited from one or both parents, depending on the inheritance pattern.
De novo mutations can be an important part of mitochondrial disease causes because they arise for the first time in the affected person. These changes may not be present in either parent but can still disrupt mitochondrial function.
Most mitochondrial disease causes are genetic, but environmental factors can sometimes worsen symptoms or trigger illness in someone with an underlying mitochondrial defect. Factors such as certain medications, infections, or toxins may increase metabolic stress on mitochondria.
Toxins are usually not the primary genetic cause of mitochondrial disease causes, but they can damage mitochondria or make an existing disorder worse. Exposure to certain drugs, chemicals, or poisons may interfere with energy production.
Infections are not usually the root genetic cause of mitochondrial disease causes, but they can trigger symptoms or reveal a hidden mitochondrial disorder. During illness, the body's energy demands rise, which can overwhelm impaired mitochondria.
Aging can contribute to mitochondrial dysfunction, but it is not the same as a primary genetic cause of mitochondrial disease causes. As people age, mitochondrial damage can accumulate and worsen energy production, especially in those with existing vulnerabilities.
Primary mitochondrial disease causes are caused by inherited or acquired genetic defects that directly affect mitochondrial function. Secondary causes refer to other conditions or exposures that impair mitochondria without being a primary mitochondrial gene defect.
Mitochondrial disease causes can vary between family members because of differences in mutation load, nuclear modifiers, inheritance patterns, and random distribution of mitochondria in cells. This can lead to different ages of onset and symptom severity.
Yes, mitochondrial disease causes can result from heteroplasmy, which means a mix of normal and mutated mitochondrial DNA within a cell. The proportion of mutated DNA often influences how severe the disorder becomes.
Yes, mitochondrial disease causes can involve defects in mitochondrial protein synthesis. If the cell cannot make the proteins needed for oxidative phosphorylation, energy production is reduced and tissues may be damaged.
Yes, mitochondrial disease causes can involve problems with mitochondrial DNA maintenance, including errors in replication, repair, or copying of mitochondrial DNA. These defects can lead to depletion or rearrangement of mitochondrial DNA and impaired energy generation.
Yes, many mitochondrial disease causes are linked to defects in oxidative phosphorylation, the process mitochondria use to make most cellular energy. When this process fails, cells cannot meet energy demands efficiently.
No, mitochondrial disease causes are not always apparent at birth. Some genetic defects are present from conception but symptoms may appear later, depending on mutation type, tissue involvement, and energy demands over time.
Understanding mitochondrial disease causes helps clinicians choose the right genetic tests, interpret symptoms, and identify affected pathways. It can also guide family counseling and help distinguish primary mitochondrial disorders from other illnesses.
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