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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 > Kearns-Sayre Syndrome

Kearns-Sayre Syndrome (KSS)

Alternative Names: Kearns-Sayre Mitochondrial Cytopathy

Disease Category: Mitochondrial Disorders

A rare disorder affecting nerves and muscles caused by genetic mutations affecting the mitochondria (specialized cell structures that produce energy). It is characterized by progressive loss of eye movement until complete paralysis (absence of movement), ptosis (eyelid drooping), and abnormal pigmentation of the membranous lining of the eyes. Other symptoms include cognitive deficits, ataxia (lack of coordination), mild skeletal muscle weakness, cardiac conduction block (defective electrical signaling in the heart), hearing loss, diabetes, and stunted growth. Most patients with this disease have a sporadic mutation in the DNA of the mitochondria (specialized cell structures that produce energy).

Research groups studying this disease

Mitochondrial Disorders
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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.