The main symptom of LHON is loss of central vision in one or both eyes.
Vision loss may be gradual, over a period lasting years, or sudden. Most
people with LHON lose their sight over a period of a few months, with a
gap of a month or two between the first and second eye being affected.
Some people with LHON have also reported tremors, lack of co-ordination, weakness and numbness of arms and/or legs.
While Multiple Sclerosis appears to be more common in people with particular mitochondiral ancestry, there is no link to the LHON genes themselves.
Finnish and Japanese studies suggest that people with LHON are more likely to have heart rhythm problems (Wolff-Parkinson-White Syndrome or Lown-Ganong-Levine syndrome). While it is estimated that in the general population the incidence of Wolff-Parkinson-White syndrome is about 1 %, the incidence found in LHON patients was around 8 or 9 %.