Leigh Syndrome: Symptoms, Causes, and Treatment Options

Has your baby stopped doing something they could do a few weeks ago? Maybe they were sitting up, or feeding well, and now they seem floppy, tired, or uninterested in the bottle. That kind of slipping backwards is one of the things that brings families to us.

Leigh syndrome is a rare inherited disorder that damages the nervous system because cells cannot make enough energy. It most often begins in infancy or childhood. But symptoms, severity, and how quickly things progress vary a great deal from one child to the next, which is why seeing a specialist early matters so much.

Overview

Leigh syndrome is a rare inherited neurological disorder that affects how the body produces energy inside cells. It belongs to a group of conditions often called mitochondrial diseases, although in some people the problem can also involve related energy pathways outside the mitochondria. Because the brain, muscles, and other organs need a constant energy supply, these tissues are especially vulnerable.

The condition usually appears in infancy or early childhood, but later-onset forms can occur in older children, teenagers, or adults. Symptoms can begin gradually or may become more noticeable after an illness, fasting, or other physical stress. Many families first recognize that a child is no longer gaining skills as expected, or has started to lose abilities they had already developed.

Leigh syndrome is not one single disease with one single cause. Instead, it is a clinical syndrome linked to changes in a number of different genes, some inherited from both parents and some passed through mitochondrial DNA. This genetic diversity helps explain why symptoms and outlook vary widely from person to person.

How Leigh Syndrome Affects the Body

The central problem in Leigh syndrome is impaired cellular energy production. When cells cannot make enough adenosine triphosphate, or ATP, organs with high energy needs begin to malfunction. The brainstem, basal ganglia, and other parts of the nervous system are commonly affected, which can lead to problems with movement, swallowing, breathing, and development.

Changes may also involve the eyes, heart, digestive system, and muscles. Some children have episodes of worsening during infections or dehydration, because these stresses increase the body’s energy demands. That is exactly why we ask families to treat infections seriously and keep up with follow-up appointments.

On imaging, especially MRI, Leigh syndrome often shows typical lesions in certain deep brain structures. Those pictures support the diagnosis, but we never read them on their own; they have to sit alongside the child’s symptoms, lab results, and genetic testing. In some cases, specialists also evaluate for related conditions within the broader group of mitochondrial diseases.

Symptoms and Signs

Symptoms of Leigh syndrome can differ depending on the person’s age of onset and the genetic cause. In babies and young children, early signs may include poor feeding, vomiting, irritability, low muscle tone, delayed milestones, or loss of previously learned skills. Parents may also notice weak sucking, poor weight gain, or reduced head control.

As the disorder affects the nervous system more clearly, symptoms may include abnormal eye movements, vision problems, stiffness, tremor, poor balance, weakness, or episodes that look like seizures. Some children develop breathing irregularities, sleep-related breathing problems, or trouble swallowing, which can raise the risk of aspiration and chest infections.

Not everyone has the same symptom pattern. Some people have a slower course with learning difficulties, coordination problems, and fatigue, while others become seriously unwell over a shorter period. Possible features can include:

• Developmental delay or regression
• Low muscle tone or muscle weakness
• Movement disorders such as dystonia or ataxia
• Feeding and swallowing difficulties
• Breathing problems
• Seizures in some patients
• Vision or hearing changes
• Poor growth or failure to thrive

Causes and Risk Factors

Leigh syndrome is caused by genetic changes that disrupt normal energy metabolism. Many cases involve genes that affect the mitochondrial respiratory chain, which is the system cells use to generate energy. Other cases are linked to defects in pyruvate metabolism or related biochemical pathways. These changes can occur in nuclear DNA or mitochondrial DNA.

The inheritance pattern depends on the gene involved. Some forms are autosomal recessive, meaning a child inherits one altered copy of a gene from each parent. Others may be X-linked or maternally inherited through mitochondrial DNA. A family history of a similar neurological condition may raise suspicion, but some families have no previous known history before a child is diagnosed.

So the risk is genetic, not something to do with lifestyle. Once the gene change is inherited, no parent can undo it. Nothing you did or did not do as a parent, and no ordinary childhood activity or environmental exposure on its own, caused this. After diagnosis, genetic counseling can help families understand recurrence risk, discuss testing for relatives, and plan future pregnancies if desired.

How Leigh Syndrome Is Diagnosed

Diagnosis begins with a detailed clinical assessment, including developmental history, neurological examination, and review of feeding, breathing, and growth. Because the signs can resemble other metabolic or neurological disorders, doctors usually take a stepwise approach. Blood and urine tests may look for lactate elevation or other metabolic clues, although normal results do not exclude the condition.

Brain MRI is often an important part of the workup because it may show changes in the basal ganglia, brainstem, or other regions typically affected in Leigh syndrome. Depending on symptoms, doctors may also assess heart function, hearing, vision, and swallowing. Electroencephalography may be used if seizures are suspected.

Genetic testing has become central to confirming the diagnosis and identifying the underlying cause. A specialist may recommend targeted mitochondrial or metabolic panels, broader genomic testing, or mitochondrial DNA analysis. In complex cases, care may involve pediatric neurology, metabolic medicine, radiology, intensive care, rehabilitation, and clinical genetics, with advanced imaging such as MRI scanning helping clarify the picture.

Treatment Options and Ongoing Care

There is currently no single cure that reverses Leigh syndrome in all patients. Treatment focuses on supporting affected organs, reducing complications, and improving quality of life. The exact plan depends on the genetic cause, age, symptoms, and severity of the disease.

Supportive care may include nutritional support, physical therapy, occupational therapy, speech and swallowing assessment, and treatment of infections or breathing difficulties. Some patients benefit from supplements or vitamins recommended by a metabolic specialist, but these should be used only under medical supervision because needs vary and evidence is not the same for every subtype.

When symptoms affect movement, mobility, breathing, or feeding, multidisciplinary care is especially important. This can include respiratory support, management of seizures, treatment for muscle stiffness or dystonia, and feeding assistance when swallowing is unsafe. Depending on individual needs, rehabilitation services such as physical therapy and rehabilitation and specialist neurological follow-up may play a central role.

Some children and adults may need urgent hospital care during acute illness because dehydration, fever, or infection can quickly increase metabolic stress. At some point in these conversations, it helps to ask about long-term planning, support at home, and palliative care where that is appropriate. For international patients, Acıbadem Health Point’s multidisciplinary specialists and JCI-accredited hospitals provide diagnosis and treatment pathways for complex neurological and metabolic conditions, including coordinated neurology care.

Daily Management, Prevention, and Family Support

Leigh syndrome cannot usually be prevented after a person has inherited the responsible genetic change, but careful day-to-day management may help reduce complications. Regular meals, good hydration, and prompt treatment of infections are often emphasized because fasting and illness can worsen metabolic stress. Families should follow the medical team’s specific advice about nutrition, activity, and emergency plans.

Many patients benefit from coordinated follow-up with several specialists, especially when growth, breathing, movement, or learning are affected. Therapists can help support posture, mobility, communication, and daily function. School planning, developmental services, and social support can also make a meaningful difference for children and caregivers.

For families considering future pregnancies, genetic counseling is an important part of care. It can explain inheritance patterns, possible carrier testing, and reproductive options in a clear and individualized way. And do not overlook your own support. Caring for a child with a rare progressive condition is exhausting, both physically and emotionally.

When to Seek Medical Care

Medical review is important if a baby or child shows developmental regression, unusual floppiness or stiffness, feeding difficulty, repeated vomiting, unexplained breathing changes, or poor growth. These signs do not always mean Leigh syndrome, but they do need professional assessment. A pediatrician or pediatric neurologist can help decide what testing is needed.

Urgent care is needed if a person with known or suspected Leigh syndrome develops breathing distress, blue lips, repeated seizures, reduced responsiveness, signs of dehydration, or sudden worsening during an infection. These situations can become serious quickly because the body may struggle to meet its energy needs.

Families should also contact the care team when swallowing becomes less safe, fatigue increases markedly, or mobility and communication decline. Early attention to changing symptoms can help doctors adjust supportive treatment, reduce complications, and plan safer care at home or in hospital.

Frequently asked questions