What is Mitochondrial Depletion Syndrome?

Mitochondrial Depletion Syndrome (MDS) refers to a group of rare genetic disorders that limit the number of mitochondria inside of cells. Mitochondria are energy generators that power the function of cells in the body. They create more than 90% of the energy in our cells. In MDS, fewer functioning mitochondria produce less energy, limiting the ability of cells to work properly.

Causes of Mitochondrial Depletion Syndrome

MDS is linked to genetic mutations in several dozen different nuclear genes. These gene mutations can be passed down from parent to child, or develop new (occur de novo) in the early embryo.. As there is often no family history of clinical disease symptoms, an MDS diagnosis can catch a family by surprise.

Symptoms of Mitochondrial Depletion Syndrome

The onset of MDS typically occurs early in life, during infancy or in the first two years. MDS can affect one or more organs in the body, including the muscular and gastrointestinal systems, the brain, and liver. Milder manifestations of the disorder can develop in teenagers and adults.

Symptoms include developmental regression, muscle weakness (hypotonia), seizures, epilepsy, difficulty feeding, and problems with liver function.

Diagnosis of Mitochondrial Depletion Syndrome

MDS etiology is diagnosed through genetic testing, often in blood. Historically, a muscle or liver biopsy was required to diagnose the condition based on the presence of mitochondrial depletion; today this testing is often secondary to confirm a genetic diagnosis or may not be needed if the primary nuclear gene cause is clearly identified by blood tests.

Treatment of Mitochondrial Depletion Syndrome

There is no cure for Mitochondria Depletion Syndrome. Genetic testing is important to identify the specific cause of the syndrome. Clinical trials for MDS are becoming more frequent and may offer therapies targeting the specific genetic causes of the disorder, or be broader based therapies to increase mitochondrial content in cells.

Other therapies that support mitochondrial enzyme deficiencies that arise in these conditions, such as mitochondrial supplement medications consisting of amino acids, antioxidants, and vitamins may help patients with metabolic disorders like MDS.

In some cases of liver failure, liver transplant may be an option.

Follow up Care for Mitochondrial Depletion Syndrome

Every person with MDS has a different set of symptoms that take time to understand and manage. Patients typically see a neurologist every 3-6 months. They will see a gastroenterologist regularly. If there is a liver issue or manifestation of the disorder in other organ systems, such as the eyes, kidneys, heart or optic nerve, patients will have yearly check-ups with appropriate specialists to monitor their symptom progression.

Sensorineural hearing loss can develop in many MDS patients and yearly Audiology testing is also recommended, with hearing aids or cochlear implants helpful in some affected individuals.