MELAS Syndrome

MELAS syndrome is a mitochondrial disease that’s caused by genetic mutations, or changes. It’s passed down by mothers even though it can affect anyone. MELAS stands for mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes. It usually becomes evident before the age of 20, but not always.


What is MELAS syndrome?

MELAS syndrome is a mitochondrial disease that mostly affects your nervous system and muscles. It also causes lactic acid to collect in your body and may result in repeated events that are similar to strokes. In fact, the word MELAS stands for mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes.

Mitochondria are the parts of most cells that are responsible for making chemical energy. The name for just one of these energy-makers is a mitochondrion. Your body uses carbohydrates to make energy, and a by-product is lactic acid.

MELAS is a genetic condition, which means people who have it are born with it. But symptoms typically don’t start until later. Most people who have MELAS show signs by or before the age of 20. But it’s possible for the disease to begin before age 2 and after age 40.

How common is MELAS syndrome?

MELAS has an estimated incidence of 1 in 4,000 people. It’s equally common in women and people assigned female at birth (AFAB) and men and people assigned male at birth (AMAB). But only women and people AFAB can pass it on to their children.


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Symptoms and Causes

What are the symptoms of MELAS syndrome?

Because mitochondria are part of all cells, MELAS syndrome can affect any organ or tissue and cause a variety of symptoms.

Almost all people with MELAS syndrome have diabetes and hearing loss before the onset of brain-related (neurologic) symptoms.

Neurologic issues that develop are due to strokes and cause the following symptoms:

Symptoms impacting the rest of your body include:

What causes MELAS syndrome?

Genetic mutations cause MELAS syndrome. Genetic mutations (changes) are changes in a sequence of your DNA, which gives your cells the information they need to work as they should. Genetic changes can happen for a number of reasons, from development to adulthood. But if you have MELAS syndrome, you inherited the mutation from your female birthing parent.

What are the risk factors for MELAS syndrome?

A risk factor for MELAS syndrome is a family history of the condition.


What are the complications of MELAS syndrome?

Complications of MELAS syndrome may include:

Diagnosis and Tests

How is MELAS syndrome diagnosed?

A healthcare provider will take a medical history and ask about your symptoms. They’ll also conduct various tests.

What tests will be done to diagnose MELAS syndrome?

Tests to diagnose MELAS syndrome may include:


Management and Treatment

How is MELAS syndrome treated?

Although there’s no cure for MELAS syndrome, healthcare providers have found ways to treat the symptoms.

Medications for MELAS symptoms

Your provider may suggest:

  • Antiseizure medications: But you should avoid valproate.
  • Coenzyme Q10 or L-carnitine: These products may increase mitochondrial energy output and slow the progression of MELAS syndrome.
  • L-arginine and L-citrulline: These products may decrease the number and effects of stroke-like episodes.
  • Insulin or metformin: This is used to treat diabetes.
  • Appropriate vaccines: People with MELAS syndrome should receive the necessary childhood vaccines, as well as annual COVID-19, flu and pneumonia vaccines.

Nonmedical treatments for MELAS syndrome

Your provider may also suggest an exercise routine for muscle strength and/or cochlear implants to help with hearing.


Can MELAS syndrome be prevented?

No, you can’t prevent MELAS syndrome. But families with this inherited condition may want to consult a genetic counselor.

Outlook / Prognosis

What can I expect if I have MELAS syndrome?

MELAS syndrome can’t be cured at this time, so you’ll have to manage it throughout your lifetime. The nature of the disease — that it can affect any organ or tissue — may mean that you’ll need a team of healthcare providers, including:

In addition, it may help you and your family to be part of a support group.

What is the life expectancy with MELAS syndrome?

You may wonder about the life expectancy of a person with MELAS syndrome, but there’s no real answer to that. Different people have different symptoms and different responses to treatments. Even people in the same family have different features of MELAS and different reactions to treatment.

It’s true, however, that MELAS syndrome can be fatal.

Living With

How can I take care of myself if I have MELAS syndrome?

You should follow the recommendations of your provider about scheduling appointments. Your provider will likely want to see you at least once per year. You may also need annual tests to check the health of your:

You should avoid drinking alcohol and smoking cigarettes because it can damage mitochondria.

Get your flu, pneumonia and other vaccines annually or as recommended.

What questions should I ask my doctor about MELAS syndrome?

It’s important to be able to get information from your healthcare team about MELAS syndrome. You likely have many questions, including:

  • What are symptoms or signs that indicate a medical emergency is close or is actually happening?
  • Should I call you or go right to an emergency room?
  • Are there food plans that can help?
  • What medications or treatments do you suggest?
  • What side effects are related to these medications or treatments?
  • Should my family receive genetic counseling?
  • Am I eligible to participate in clinical trials?
  • Can you suggest a support group for me and my family?

A note from Cleveland Clinic

Hearing that you or your child have a mitochondrial disease can be overwhelming. You might not have heard of mitochondria, but that’s one reason it’s important to get clear information on MELAS syndrome and what it means to have it. It’s also another reason to find a healthcare team that will cover all the bases in terms of diagnosis, treatment and management.

Don’t hesitate to ask questions and get the answers that you need. And get as much help as you need from your healthcare providers and the people around you. Feeling supported – and being supported – can make all the difference in the world.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 07/24/2023.

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