Severe lactic acidosis. Prominent ragged-red fibers. Death due to respiratory failure usually occurs prior to one year of age. Following normal early development until one year old, weakness appears and worsens rapidly, causing respiratory failure and death typically within a few years. Severe lactic acidosis.
Death is typical within the first year.
Progressive external ophthalmoplegia, limb weakness, peripheral neuropathy, digestive tract disorders, leukodystrophy, lactic acidosis, ragged red fibers. Leigh Syndrome may result if the percentage of mutation is high enough. Single mitochondrial DNA deletions. Inheritance is usually sporadic. Those who survive infancy usually develop Kearns-Sayre Syndrome .