Mitochondrial Myopathies, Chronic Progressive External Ophthalmoparesis, and Kearns-Sayre Syndrome

Abstract

Primary mitochondrial myopathies (PMM) have been defined as genetically determined disorders leading to defects of oxidative phosphorylation and affecting predominantly, but not exclusively, skeletal muscle. Manifestations lead from isolated mitochondrial myopathy to chronic progressive external ophthalmoparesis and Kearns-Sayre syndrome. In contrast to many other mitochondrial disorders, diagnosis still requires the morphological and genetic workup of a muscle biopsy which also is very helpful in differential diagnosis. The exact identification of the underlying genetic cause is a prerequisite for appropriate genetic counselling in affected families. While disease-modifying therapies are in development, many symptom management approaches including ptosis surgery are already available to improve activities of daily living and quality of life.