LHON

Leber s hereditary optic neuropathy (LHON) is caused by a mutation of the ND1 gene encoding an eie-ment of complex I of the eiectron transport chain and other simiiar mutations. 

The pathophysioiogy of LHON arises from impaired oxidative phosphorylation, leading to blindness In many patients by early adulthood due to optic nerve death. 

The ND1 gene resides on the DNA of the mitochondria and is passed on to offspring by the egg cells of the mother, so there is no male-to-male transmission of LHON (see Chapter 13). 

The answer is B. LHON often has an onset in early adulthood. It is a mitochondrial disorder usually resulting from a mutation in one of the proteins of the electron transport chain, particularly complex I, encoded by the mitochondrial genome so there is no chance that the patient can pass the disorder to his children (see Chapter 13). Cataracts would have been detected as opacity in the lenses, and glaucoma would have been identified by an elevated intraocular pressure. Macular degeneration is also associated with central vision loss but is found mainly in patients over age 65. 

LHON (Leber s hereditary optic neuropathy) causes blindness arising from mutations in the ND1 gene encoding complex I of the electron transport chain (see Chapter 7). 

MELAS, Mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes CPEO, chronic progressive external ophthalmoplegia LHON, Leber hereditary optic neuropathy NARP, neurogenic muscle weakness, ataxia, and retinitis pigmentosa NIDDM, non-insulin-dependent diabetes mellitus TER, termination. 

LHON), in which the pallor begins 2 to 4 weeks after vision loss. 

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