Mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is a genetic condition that affects the nervous system and muscles, typically in children.

MELAS syndrome is a genetic condition that affects the activity of mitochondria of cells in the body. Mitochondria help turn food into energy, which allows cells to function as usual. Due to issues with mitochondria, MELAS syndrome disrupts this process and causes a range of symptoms, typically in the nervous system.

The United Mitochondrial Disease Foundation suggests that around 1–16 out of 100,000 adults have MELAS syndrome. However, the disease typically begins during childhood, and symptoms may sometimes develop before 2 years old. The symptoms progressively worsen over time and typically become fatal.

MELAS syndrome causes early symptoms that include seizures and headaches. It may lead to stroke-like episodes, as well as motor and intellectual disabilities. There is currently no cure for MELAS syndrome, but doctors can manage some symptoms of the condition using a combination of treatments.

This article discusses the causes and symptoms of MELAS syndrome, what to expect from the treatment, and how the condition progresses.

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MELAS syndrome is a genetic condition that typically begins during childhood. The condition causes symptoms that primarily affect the nervous system and muscles. The nervous system includes the brain, spinal cord, and nerves throughout the body.

MELAS syndrome causes a wide range of symptoms, including stroke-like episodes. These episodes have similar characteristics to a stroke, such as a lack of consciousness and numbness down one side of the body. The symptoms worsen over time and are typically fatal.

The syndrome is present in around 1–16 out of 100,000 adults. It is one of the most common types of mitochondrial disease, which together affect around 1 in 4,000 people. Mitochondrial diseases refer to any condition that affects how mitochondria function in cells.

MELAS syndrome is the result of alterations in mitochondrial DNA. Mitochondria are present in cells and develop according to instructions from mitochondrial DNA. Mitochondrial DNA is within the mitochondria only, unlike autosomal DNA, which is in the 22 pairs of chromosomes.

People inherit mitochondrial DNA from their mothers as mitochondrial DNA in sperm typically disappears during fertilization. As such, people typically inherit MELAS syndrome from their mothers, but there are rare cases where variations occur at random without any inheritance.

Around 80% of people with MELAS syndrome have an alteration in the MT-TL1 gene. This gene provides instructions for making transfer RNA, which helps to assemble proteins that form mitochondria. However, variations in other mitochondrial DNA genes can also cause MELAS syndrome, including:

These variations in mitochondrial DNA affect their ability to convert the energy from food into a form that cells can use. In particular, it affects their ability to make proteins, use oxygen, and produce energy.

Individuals with MELAS syndrome typically develop as usual until their symptoms start between 2 and 10 years old. Symptoms that someone with MELAS syndrome might experience can vary substantially due to the range of bodily systems the condition affects.

However, a distinguishing feature of MELAS syndrome is its capacity to cause stroke-like episodes. These episodes may result from an insufficient level of nitric oxide in the small blood vessels of the brain.

Other symptoms of MELAS syndrome might include:

The most common early symptoms of MELAS syndrome include headaches, loss of appetite, and vomiting. Some of these symptoms are due to lactic acidosis. This is where the body is unable to properly clear acid from the blood, causing it to build up.

MELAS syndrome can also lead to other issues, such as:

A medical professional will typically use a combination of medical imaging and tests to diagnose MELAS syndrome.

For example, doctors may use MRI scans to identify lesions and other issues in the brain that could be due to MELAS syndrome. They might also measure the amount of lactate in the blood or cerebrospinal fluid. They could also take samples of muscle tissue to identify damage from the condition.

Doctors may also use electrocardiograms to detect issues with the heart that may be due to MELAS syndrome, such as cardiomyopathy. These tests measure electrical activity in the heart to check for abnormalities.

In some cases, a doctor may also order genetic testing to identify variations that can cause MELAS syndrome.

Currently, there is no cure or specific treatment for MELAS syndrome. A medical professional will typically prescribe treatments that can address specific symptoms and improve daily functioning. Possible treatment options may include:

  • anticonvulsant drugs to reduce seizures
  • cochlear implants to treat hearing impairments
  • exercise training to improve physical fitness and reduce lactate levels
  • L-arginine to reduce the symptoms of stroke-like episodes
  • vitamins that could increase energy production by mitochondria, such as L-carnitine
  • insulin for diabetes

There are also clinical trials underway to identify new treatments for MELAS syndrome. For example, ongoing research is investigating whether the antioxidant compound idebenone can help improve symptoms in people with MELAS syndrome and other mitochondrial conditions.

People with MELAS syndrome experience symptoms that worsen over time. The symptoms can start early and last several years. These symptoms can quickly become highly disruptive to daily living. For example, people can experience frequent stroke-like episodes or difficulty communicating.

The types of symptoms that people experience vary substantially. Doctors may be able to manage some of these symptoms depending on their type and severity. However, the symptoms will worsen and can occur with other complications, such as dementia or diabetes.

The United Mitochondrial Disease Foundation state that most people with MELAS syndrome survive for around 17 years following the onset of seizures or other nervous system symptoms.

MELAS syndrome is a rare genetic condition that typically begins during childhood. People with MELAS syndrome may experience a wide range of symptoms that worsen over time. A hallmark symptom of MELAS syndrome is stroke-like episodes, which can be similar to the symptoms of a stroke.

Early symptoms of MELAS syndrome may include headaches, loss of appetite, and vomiting. People with MELAS syndrome typically experience a deterioration of their nervous systems and muscles. This can lead to serious complications and is eventually fatal. At present, there is no cure for MELAS syndrome. However, doctors may be able to manage some symptoms of the condition with various treatment options.