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Diseases Studied

The Rare Diseases Clinical Research Network is an NIH-funded research network of 20 active consortia or research groups working to advance treatment for diseases that are rare. Use the search tools on this page to find the diseases we currently study. You can reach out to the indicated consortia or research groups for more information on those diseases and studies underway.

This network focuses on clinical research and does not generally support clinical care outside of research activities. To learn about other rare diseases, please visit the Genetic and Rare Diseases Information Center (GARD), which is an NIH program that helps the public find reliable information about rare and genetic diseases. Their staff are specialists. Contact them at 1-888-205-2311 or email

All Diseases > Maternally Inherited Leigh Syndrome

Maternally Inherited Leigh Syndrome (MILS)

Alternative Names: Maternal Inherited Infantile or Juvenile Subacute Necrotizing Encephalopathy; Maternal Inherited Subacute Necrotizing Encephalomyelopathy

Disease Category: Mitochondrial Disorders

A rare disorder caused by genetic mutations in the DNA of mitochondria (specialized cell structures that produce energy) which leads to severe brain damage. Mitochondrial DNA can only be passed along from mothers, making this disorder "maternally inherited." Symptoms manifest in infancy, including psychomotor regression (loss of mental and motor skills), dysphagia (difficulty swallowing), feeding and growth problems, hypotonia (low muscle tone), diarrhea, vomiting, involuntary muscle movements, ataxia (lack of coordination), peripheral neuropathy (sensory loss and muscle weakness in the extremities), lactic acidosis (high blood lactate levels), hypertrophic cardiomyopathy (heart muscle thickening), and respiratory failure.

Research groups studying this disease

Mitochondrial Disorders
NAMDC logo

North American Mitochondrial Disease Consortium (NAMDC)

Improves quality of life for people affected by mitochondrial disease through education, outreach, advocacy, and clinical research initiatives.

Promotes research and education for the diagnosis, treatment, and cure of mitochondrial disorders while providing support to those affected.