Abstract
Leber's hereditary optic neuropathy (LHON) is a maternally inherited disease that is characterized by acute, severe, bilateral visual loss in healthy young persons. The central visual loss is acute or subacute at onset, painless, and accompanied by large cecocentral scotomata and dyschromatopsia. Visual loss is virtually always bilateral and is usually synchronous in onset. The visual symptoms usually occur in isolation, although abnormalities of cardiac conduction have been convincingly demonstrated in some families.1 Leber's hereditary optic neuropathy is strictly maternally inherited and passes to future generations only through women.1,2 An affected man never has offspring with LHON, while a woman in a family with LHON may have affected children although she herself is visually normal (ie, she acts as a carrier of the genetic trait). Although the vast majority of cellular DNA is con See also p 1417. tained in the nucleus, mitochondria also contain independently inherited DNA.