WHAT IS LEIGH SYNDROME

Leigh syndrome (sometimes called Leigh’s disease) is a rare and severe neurometabolic disorder and a type of primary mitochondrial disease. Mitochondria extract energy from your food to help your cells do work. All of the cells in our body (except red blood cells) have mitochondria.

 

Mitochondria play a crucial role in converting food and oxygen into energy. In the case of Leigh syndrome, there is dysfunction in the mitochondria within cells responsible for supplying energy to the brain, nerves, and spinal cord.

 

Leigh syndrome is  named after Dr. Denis Leigh, a neuropathologist in London, who first described the condition in 1951. Leigh syndrome is characterized by specific brain lesions, which are a unique feature of the condition. These lesions typically appear in the basal ganglia, brainstem, and cerebellum. The affected areas often exhibit bilateral symmetrical necrotic or degenerative changes. These distinctive lesions are one of the key diagnostic markers used in identifying Leigh syndrome.

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Leigh syndrome affects primarily babies and young children, with symptoms usually starting between the ages of 3 months and 2 years. Leigh syndrome can also occur in teenagers and adults, although this is less common. 

 

Our DNA is made up of DNA in the nucleus of our cells (‘nuclear’ DNA, half of which is inherited from the father and half of which is inherited from the mother, and mitochondrial DNA (which is in the mitochondria, inherited from the mother). 

 

Leigh syndrome can be caused by nearly 100 genes and nuclear DNA and 16 genes in mitochondrial DNA, with more genes continuing to be discovered. Your doctor may order some genetic tests in blood (or a cheek swab, or a urine sample) in order to arrive at the exact genetic diagnosis.  

 

Although Leigh syndrome is a genetic disease, we are not always able to identify a genetic variant- a change in either nuclear or mitochondrial DNA- that leads to Leigh syndrome. In cases like this, additional testing, such as a muscle biopsy or skin biopsy, may be recommended.
 

Leigh syndrome affects at least 1 in 40,000 individuals. However, this number may be underestimated. Population variations, misdiagnosis, and even a reluctance by some medical professionals to use the term “Leigh syndrome” likely impact measurements of how many people actually have the disease.

 

Certain populations have higher frequencies of the disease, including the Saguenay Lac-Saint region of Quebec, Canada and the Faroe Islands.

 

Today, Leigh syndrome has no cure. The disease is progressive, and is likely to gradually worsen over time. Unfortunately, some individuals with Leigh syndrome do not survive beyond childhood, while others may have a longer lifespan but still face significant challenges. .

 

It is important to recognize that Leigh syndrome can manifest very differently in each individual, in some cases it progresses fast, in other cases it progresses slowly. Some individuals are affected more severely than others. Additionally, different genes that cause Leigh syndrome can manifest differently. Therefore, it is important to be careful when reading stories of others online or asking questions on social media, as they may not apply to your individual situation and can add to an emotional stress and burden.

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