Leber Hereditary Optic Neuropathy – LHON
Leber hereditary optic neuropathy (LHON) is characterized by optic nerve dysfunction that leads to painless, subacute loss of central vision. Disease affects mainly young adult males. LHON is caused by mutations in mtDNA and it is transmitted by maternal inheritance. Approximately 95% of individuals with LHON have one of three point mutations of mitochondrial DNA (m.3460G>A, m.11778G>A, or m.14484T>C).
The prevalence of LHON is estimated to 1:50 000. The m.11778G>A mutation accounts for about 90% of Asian cases and 50 to 70% of Caucasian cases. The m.14484T>C mutation occurs about 86% cases in Quebec, Canada. Frequency of the m.3460G>A mutation is about 20% in European LHON patients.
Indications for genetic testing:
1. Confirmation of clinical diagnosis
2. Genetic counseling