Disease Directory Kearns-Sayre Syndrome
Mitochondrial

Kearns-Sayre Syndrome

Also known as: KSS, oculocraniosomatic syndrome, mtDNA large deletion

Prevalence

Approximately 1–3 per 100,000

Onset

Before age 20

Type

Rare mitochondrial disease

Gene

mtDNA deletion

About Kearns-Sayre Syndrome

Kearns-Sayre syndrome is a sporadic mitochondrial disease defined by the triad of onset before age 20, chronic progressive external ophthalmoplegia, and pigmentary retinopathy, plus at least one of cardiac conduction defects, cerebellar ataxia, or elevated CSF protein. It is caused by large-scale single deletions in mitochondrial DNA, typically several kilobases in size, arising de novo and leading to multisystem dysfunction. Cardiac involvement, including complete heart block, is the most life-threatening feature and may require pacemaker implantation.

Common Clinical Features

Chronic progressive external ophthalmoplegia (ptosis and ophthalmoplegia) Pigmentary retinopathy Cardiac conduction defects and heart block Cerebellar ataxia Proximal muscle weakness Elevated cerebrospinal fluid protein Sensorineural hearing loss and endocrine dysfunction

Clinical Trial Eligibility Tips

What to know before applying to Kearns-Sayre Syndrome trials.

Molecular confirmation of a large-scale mtDNA deletion by Southern blot or long-range PCR is required for most KSS trials; blood heteroplasmy may be low, so muscle tissue testing is preferred.

Cardiac monitoring history, including Holter and ECG, is a standard pre-screening requirement given the high risk of sudden cardiac death from conduction defects.

Trials may exclude patients with pacemakers if study devices or imaging protocols are incompatible; confirm your pacemaker model details in advance.

Patient Resources

Patient Organization

United Mitochondrial Disease Foundation

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Natural History Registry

North American Mitochondrial Disease Consortium (NAMDC) Registry

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Orphanet

European reference resource for rare diseases (ORPHA:480)

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NORD

National Organization for Rare Disorders

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Find recruiting Kearns-Sayre Syndrome trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for Kearns-Sayre Syndrome. Updated daily.

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