LHON and extraocular features

LHON is typically a monosymptomatic disease but additional features such as cardiac conduction defects, peripheral neuropathy, dystonia, and myopathy have been reported as occurring more frequently among LHON carriers. There is also a well-reported association between the three primary mitochondrial DNA LHON mutations and a multiple sclerosis-like illness, especially among female carriers (so-called Harding's disease). This presentation will critically appraise the extraocular features that have been associated with LHON and how these atypical phenotypes are potentially informing us about important disease mechanisms.