Which condition is caused by mitochondrial DNA mutations passed through maternal inheritance?

• A. Retinitis pigmentosa
• B. Dominant optic atrophy
• C. Leber's hereditary optic neuropathy
• D. Best disease

Answer: (C)

Leber's hereditary optic neuropathy is caused by mutations in mitochondrial DNA, which are inherited exclusively from the mother. Mitochondria come from the egg cell, and paternal mitochondria are typically not transmitted to the offspring, so affected mothers pass the mutation to all their children, though the expression can be variable due to heteroplasmy (a mix of normal and mutant mitochondria) and other factors. This maternal inheritance pattern distinguishes LHON from the other eye diseases listed, which are due to nuclear gene mutations with different inheritance modes. LHON specifically affects retinal ganglion cells and the optic nerve, often causing subacute central vision loss in young adults.