Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS) is a rare mitochondrial disorder characterized by a triad of features: onset before age 20, progressive external ophthalmoplegia (weakness or paralysis of the eye muscles), and pigmentary retinopathy (abnormal pigment deposits in the retina). It is caused by large-scale deletions of mitochondrial DNA (mtDNA), typically ranging from 1,000 to 10,000 base pairs, which impair the ability of mitochondria to produce energy through oxidative phosphorylation. Because mitochondria are present in nearly all cells, KSS can affect multiple organ systems throughout the body. In addition to the defining ocular features, patients commonly develop cardiac conduction defects (such as heart block), which can be life-threatening and may require pacemaker implantation. Other frequent manifestations include cerebellar ataxia (impaired coordination), elevated cerebrospinal fluid protein levels, sensorineural hearing loss, short stature, endocrine abnormalities (including diabetes mellitus, hypoparathyroidism, and growth hormone deficiency), skeletal muscle weakness, and cognitive impairment. Renal tubular acidosis and other organ-specific complications may also occur. The progressive nature of the disease typically leads to increasing disability over time. There is currently no cure for Kearns-Sayre syndrome, and treatment is primarily supportive and symptomatic. Cardiac monitoring is essential, as sudden cardiac death from complete heart block is a recognized risk, and prophylactic pacemaker placement is often recommended. Supplementation with coenzyme Q10, L-carnitine, and B vitamins is frequently used, though evidence for their efficacy remains limited. Ptosis (drooping eyelids) may be managed surgically, and endocrine deficiencies are treated with appropriate hormone replacement. A multidisciplinary approach involving ophthalmology, cardiology, neurology, and endocrinology is critical for optimal management.

Common questions about Kearns-Sayre syndrome