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What Are Mitochondrial Disorders and How Common Are They?

Mitochondrial disorders are genetic disorders that affect the mitochondria—an important cellular structure. Within each cell are structures called organelles that perform a specific function, like protection or cell division. Mitochondria are responsible for generating more than 90 percent of the cellular energy that sustains organ function, and therefore our lives.

How Do Mitochondrial Disorders Affect Health?

Mitochondria act as a digestive system for cells. They take in nutrients from the food and beverages we consume and turn them into energy-rich molecules that are then used by the cell to perform other functions, like growth and division. Certain cells like muscle and liver cells require thousands of mitochondria, while other cells like red blood cells do not need any.

Mitochondrial disorders occur when the mitochondria cannot produce enough energy for cells to use, and therefore are unable to properly carry out their functions. When this happens, it can lead to serious symptoms. 

The symptoms of mitochondrial conditions can vary greatly because they can affect cells in any system of the body, and sometimes in more than one. Mitochondrial disorders affect each person differently, but common symptoms can include:

  • Muscle weakness and/or intolerance to exercise
  • Gastrointestinal (GI) disorders
  • Increased risk of infection
  • Movement disorders
  • Respiratory complications

How Common Are Mitochondrial Disorders?

It is estimated that nearly two million people in the United States have a mitochondrial disorder, and that about 1,000 to 4,000 people each year are born with a mitochondrial condition. Mitochondrial disorders can affect people of all ages but are primarily diagnosed in children. 

How Do Mitochondria Disorders Occur?

Mitochondrial disorders can be inherited (a gene is passed onto a child from the mother, the father, or both) or the result of a random error. Genetic mutations associated with mitochondrial disorders are caused by defects in either the DNA of the mitochondria or the nucleus.

Mitochondrial disorders can develop in the following ways:

  • Autosomal recessive: Two copies of a mutated gene are needed in order for the disorder to develop. A genetic mutation is inherited from both the mother and the father.
  • Autosomal dominant: Only one mutated gene is needed in order for the disorder to develop. The genetic mutation can be inherited from either the mother or the father.
  • Mitochondrial: The mitochondria have their own DNA, apart from DNA found in the cell’s nucleus. Some mitochondrial disorders occur as the result of a genetic mutation in the mitochondrial DNA—this is referred to as mitochondrial inheritance. Mitochondria are only passed down from the mother. If a male inherits a disorder related to mitochondrial DNA, he cannot pass it onto his children. 
  • Random mutation: Sometimes, a mistake in cell division can result in a random error in DNA. These types of mutations are not inherited by either parent.

Treatment Options for Mitochondrial Disorders

There currently is no cure for mitochondrial disorders. Treatments consist of relieving symptoms and delaying or halting the progression of the disease. Current treatments for mitochondrial disorders include:

  • Diet therapy as prescribed by a doctor and guided/monitored by a registered dietitian
  • Vitamins and supplements as prescribed by a doctor
  • Exercise as indicated by a doctor
  • Therapies specific to the symptoms of each individual, like speech therapy, respiratory therapy, and physical therapy


Sources:

https://my.clevelandclinic.org/health/diseases/15612-mitochondrial-diseases
https://rarediseases.info.nih.gov/diseases/7048/mitochondrial-genetic-disorders
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5967365/
https://www.nature.com/scitable/topicpage/eukaryotic-cells-14023963/
https://www.toppr.com/guides/biology/the-fundamental-unit-of-life/cell-organelle/
https://www.ncbi.nlm.nih.gov/pubmed/21698761
https://my.clevelandclinic.org/health/diseases/15612-mitochondrial-diseases/management-and-treatment