Neuromuscular diseases

Leigh syndrome

A progressive brain disease that usually begins in infancy. Energy production in the cells is impaired. Movement, swallowing and breathing can be affected.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

Prepare an emergency card

This page is translated from the Turkish original.

This disease is followed through the “Neuromuscular diseases” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

The mitochondria, the cells' power plants, cannot produce enough energy. Tissues that need a lot of energy, such as the brain, muscles and heart, are affected most. Areas of damage form in the parts of the brain that control movement, balance, swallowing and breathing. A change in one of more than 110 genes can cause this.

Which symptoms can occur?

Symptoms usually begin in the first year of life. Sometimes they appear after an illness with fever. In a small number of people, it begins in adulthood and progresses more slowly.

Vomiting, diarrhea and difficulty swallowing (common first symptoms)
Poor weight gain
Loss of skills already gained
Floppy muscles, involuntary muscle contractions and balance problems
Weakness of the eye muscles or involuntary eye movements
Breathing problems (common)
Thickening of the heart muscle (sometimes)
Seizures, also called fits

How is it diagnosed?

A brain MRI shows areas of damage typical of this disease. Lactate may be high in the blood, urine or cerebrospinal fluid. The diagnosis is confirmed with a genetic test.

Treatment and care

There is not yet a proven treatment for Leigh syndrome. Treatment is aimed at symptoms and support. This includes nutritional support, physiotherapy, and care for seizures and breathing. In some subtypes, vitamin supplements or a special diet may be helpful. Many specialists work together as a team. Research is ongoing. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

The pattern of inheritance depends on the cause. It is most often passed on through recessive inheritance. For a couple who are both carriers, the chance of having an affected child is 1 in 4 in each pregnancy. Recessive diseases can be more common when relatives marry each other. In about one in five cases, the disease is passed on from the mother through the mitochondria. Rarely, it is X-linked or caused by a new gene change. Genetic counselling clarifies the family's risk.

Source: MedlinePlus Genetics: Leigh syndrome · NORD: Leigh Syndrome · GeneReviews: Mitochondrial DNA-Associated Leigh Syndrome Spectrum

Key facts

How common is it?: Prevalence: 1-9 per 100 000 (Europe)
How is it inherited?: Autosomal recessive · Mitochondrial inheritance · X-linked recessive
When does it usually start?: Any age
Gene(s) involved: IARS2
Reliable sources: MedlinePlus (for families) · Orphanet · GeneReviews (for doctors)

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

Türkiye Kas Hastalıkları Derneği · For the disease group · İstanbul

For all rare diseases: Nadir Hastalıklar Federasyonu

Links checked on October 8, 2026.

Guides related to this disease

Rare disease at school · Telling the school, medicines and emergency plan, inclusion and BEP, support education room, absences, LGS/YKS arrangements, peer bullying.

Support and help

In an emergency in Türkiye, call 112.
For psychological and social support, the ALO 183 Social Support Line (24/7, free from within Türkiye): alo183.aile.gov.tr
For carers: Looking after yourself as a caregiver
Preparing for a doctor visit · Collect your questions and symptom notes on one page, then print it and take it with you.

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about Leigh syndrome

GlobalResearch and clinical trialsAugust 26, 2026

Data on the first 74 patients published from an international study following the course of Leigh syndrome

People with Leigh syndrome are followed regularly at five centers, every 3-6 months.

Peer-reviewed publicationLeigh syndrome

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

Could this trial be suitable for us?
If we take part, how would current treatment and check-ups be affected?
Where does the trial take place, and how are travel and accommodation handled?
What happens if we want to leave the trial?

ClinicalTrials.gov lists 2 active interventional studies for this disease. None is recruiting right now; none has a site in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

A Dose-ranging Study of TTI-0102 in Adults and Children With Leigh Syndrome Spectrum (LSS)
Middle stage: the effect is being tested in a small group · Phase 2 · investigational (experimental)Not yet recruitingNCT06990984
Sirolimus for Leigh Syndrome
Middle stage: the effect is being tested in a small group · Phase 2 · investigational (experimental)Enrolling by invitationNCT06843811

See all studies on ClinicalTrials.gov · Joining clinical trials

Neuromuscular diseases: other news

InternationalResearch and clinical trialsOctober 1, 2026

Experimental oral RIPK1 inhibitor showed no benefit in ALS in a phase 2 trial

The HIMALAYA study, published in The Lancet Neurology, examined an experimental drug in patients with ALS (amyotrophic lateral sclerosis).

Peer-reviewed publicationALS

TürkiyeResearch and clinical trialsSeptember 25, 2026

Guillain-Barré after COVID-19 in Istanbul: the type affecting the nerve sheath was more common

A multicenter study in Istanbul compared patients with Guillain-Barré syndrome.

Peer-reviewed publicationGuillain-Barré

USANew treatments and approvalsSeptember 18, 2026

First drug for balance problems in ataxia-telangiectasia, levacetylleucine, approved in the USA

The US Food and Drug Administration (FDA) approved levacetylleucine for balance and walking problems in ataxia-telangiectasia (A-T).

Official drug approvalA-T

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:506 · ICD-11 5C53.24

Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.