About Mitochondrial Disease

Mitochondria, also called organelles, are cellular structures that primarily produce energy for the cell in the form of ATP. The number of mitochondria per cell varies greatly by tissue type, but can be as great as 4,000. Most DNA within a cell is contained in chromosomes; however, mitochondria have their own distinct DNA, called mitochondrial DNA (mtDNA). Mitochondrial DNA contains 37 genes, all essential for normal mitochondrial function.

Mitochondrial diseases occur when the structures within a cell (organelles) that produce energy for that cell, malfunction. Approximately 1,000 children a year in the U.S. are born with some form of mitochondrial disease. Most often, mitochondrial disorders are inherited. However, an uncertain percentage of patients acquire symptoms due to other factors, including exposure to mitochondrial toxins and aging. Common symptoms can include, but are not limited to:

  • Muscle weakness
  • Gastrointestinal disorders
  • Neurological problems, such as seizures, and cardiac, liver or respiratory disease
  • Developmental delay
  • Poor growth
  • Increased susceptibility to infection

Mitochondrial medicine is a new and rapidly developing medical subspecialty. Even though conditions with an underlying mitochondrial cause were noted as far back as the late 1800s, it was only in 1959 that the first patient was diagnosed with a mitochondrial disorder. In 1963, researchers discovered that mitochondria have their own DNA — mtDNA — or "blueprint," which is different from the nuclear DNA (nDNA) found in a cell's nucleus. This discovery has aided the expansion of mitochondrial genetics and medicine.

Today, researchers have identified over 40 different mitochondrial disorders with unique genetic features. The common factor among these diseases is that the mitochondria are unable to completely burn food and oxygen to generate energy, which is essential for normal cell function.

Using samples collected by the Mitochondrial Disease Biobank, researchers are able to learn more about a group of diseases collectively known as mitochondrial disorders. These include:

  • Alpers' progressive sclerosing poliodystrophy (Alpers' disease)
  • Leber optic neuropathy
  • Barth syndrome
  • Leigh and Leigh-like syndrome
  • Chronic progressive external ophthalmoplegia (CPEO)
  • Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS)
  • Dominant optic atrophy
  • Myoclonic epilepsy with ragged red fibers (MERRF)
  • Friedreich's ataxia
  • Neuropathy, ataxia, and retinitis pigmentosa (NARP)
  • Hereditary paraganglioma
  • Pearson syndrome
  • Hereditary spastic paraplegia
  • Wolfram syndrome
  • Kearns-Sayre syndrome