Autosomal dominant Kearns-Sayre syndrome

Area of Science:

• Neurology
• Genetics
• Ophthalmology

Background:

• Kearns-Sayre syndrome (KSS) is characterized by external ophthalmoplegia, retinal pigmentary degeneration, and heart block.
• Associated symptoms can include skeletal muscle weakness, ataxia, deafness, and endocrine disturbances.

Observation:

• A study investigated a two-generation family with autosomal dominant KSS, examining 15 members.
• Clinical manifestations varied, with seven experiencing external ophthalmoplegia, six with electrocardiographic abnormalities, and six with limb weakness.

Findings:

• Muscle biopsy revealed "ragged-red fibers," abnormal lipid accumulation, and enlarged mitochondria with inclusions, consistent with mitochondrial myopathy.
• The study highlighted significant variability in genetic expression among affected individuals.
• Asymptomatic carriers were identified, underscoring the need for comprehensive family screening.

Implications:

• Recognizing the variable expressivity of KSS is crucial for accurate diagnosis and genetic counseling.
• Family-wide examinations are essential to uncover the full hereditary pattern and identify subclinical cases.
• The absence of consistent biochemical markers necessitates reliance on clinical and pathological findings for KSS diagnosis.