Kearns–Sayre syndrome

Fundus of patient with retinitis pigmentosa, mid stage

Kearns–Sayre syndrome (KSS) is a rare neuromuscular disease caused by defects in the mitochondrial DNA. It is characterized by a triad of symptoms: progressive external ophthalmoplegia, pigmentary retinopathy, and onset before the age of 20. KSS is a subtype of mitochondrial myopathy.

Signs and Symptoms

The primary symptoms of Kearns–Sayre syndrome include:

• Progressive external ophthalmoplegia: Weakness or paralysis of the eye muscles, leading to drooping eyelids (ptosis) and limited eye movement.
• Pigmentary retinopathy: A condition where the retina is damaged, leading to vision loss.
• Onset before the age of 20.

Additional symptoms may include:

• Cardiac conduction defects: Abnormalities in the heart's electrical system, which can lead to arrhythmias.
• Ataxia: Lack of muscle coordination.
• Deafness: Hearing loss.
• Diabetes mellitus: A metabolic disorder characterized by high blood sugar levels.
• Short stature: Below-average height.
• Endocrine disorders: Such as hypoparathyroidism and growth hormone deficiency.

Causes

Kearns–Sayre syndrome is caused by deletions in the mitochondrial DNA (mtDNA). These deletions result in the loss of essential genes required for mitochondrial function. The condition is typically sporadic, meaning it usually occurs without a family history.

Diagnosis

Diagnosis of Kearns–Sayre syndrome is based on clinical evaluation, patient history, and genetic testing. Key diagnostic criteria include:

• Presence of the triad of symptoms (ophthalmoplegia, pigmentary retinopathy, and onset before age 20).
• Muscle biopsy showing ragged red fibers.
• Genetic testing revealing deletions in the mitochondrial DNA.

Treatment

There is no cure for Kearns–Sayre syndrome, and treatment is primarily supportive and symptomatic. Management strategies include:

• Cardiac monitoring and pacemaker implantation for cardiac conduction defects.
• Cochlear implants or hearing aids for hearing loss.
• Physical therapy and occupational therapy to manage muscle weakness and ataxia.
• Endocrine therapy for associated endocrine disorders.

Prognosis

The prognosis for individuals with Kearns–Sayre syndrome varies. While some patients may experience a relatively stable course, others may have progressive symptoms leading to significant disability. Early diagnosis and management of symptoms can improve the quality of life.

Related Pages

• Mitochondrial myopathy
• Progressive external ophthalmoplegia
• Pigmentary retinopathy
• Cardiac conduction defects
• Ataxia
• Diabetes mellitus
• Endocrine disorders

External Links

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Medical condition