While the balance between risks and benefits of HRT remains controversial, the decision to start HRT requires an individualized approach based on the patients context. While not applicable for all post-menopausal women, prophylactic (and therapeutic) HRT should be considered in all female carriers of a known LHON mutation given the substantial risk of vision loss associated with menopause. Epidemiology
In Northern European populations about one in 9,000 people carries one of the three primary LHON mutations. There is a prevalence of between 1:30,000 to 1:50,000 in Europe. The LHON ND4 G11778A mutation is the primary mutation in most of the world, with 70% of Northern European cases and 90% of Asian cases. Due to a Founder effect, the LHON ND6 T14484C mutation accounts for 86% of LHON cases in Quebec, Canada.More than 50% of males with a mutation and more than 85% of females with a mutation never experience vision loss or related medical problems. The particular mutation type may predict the likelihood of penetrance, severity of illness and probability of vision recovery in the affected. As a rule of thumb, a woman who harbors a homoplasmic primary LHON mutation has a ~40% risk of having an affected son and a ~10% risk of having an affected daughter.Additional factors may determine whether a person develops the signs and symptoms of this disorder. Environmental factors such as smoking and alcohol use may be involved, though studies of these factors have produced conflicting results.
In these trials, participants affected by LHON with the G11778A mutation will have a virus expressing the functional version of ND4—the gene mutated in this variant of LHON—injected into one eye. A sham injection will be administered to the other eye for comparison. It is hypothesized that introduction of the viral vector may be able to rescue the function of the mutant gene. Preliminary results have demonstrated tolerability of the injections in a small number of subjects.Stealth BioTherapeutics is investigating the use of elamipretide (MTP-131), a mitochondrial protective agent, as a therapy for LHON. Elamipretide helps stabilize cardiolipin—an important component of mitochondrial inner membranes—and has been shown to reduce damaging reactive oxygen species in animal models. See also
Amaurosis
Dominant optic atrophy
Glaucoma
Ischemic optic neuropathy
Optic atrophy
Toxic and nutritional optic neuropathy

References
Further reading
Lebers hereditary optic neuropathy at NLM Genetics Home Reference
Kerrison JB, Newman NJ (1997). "Clinical spectrum of Lebers hereditary optic neuropathy" (IFOND reprints). Clin. Neurosci. 4 (5): 295–301. PMID 9292259. Carelli V, Ross-Cisneros FN, Sadun AA (January 2004). "Mitochondrial dysfunction as a cause of optic neuropathies". Prog Retin Eye Res. 23 (1): 53–89. doi:10.1016/j.preteyeres.2003.10.003. PMID 14766317. S2CID 15862778. External links

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