Leber Hereditary Optic Neuropathy (LHON)

Excerpt

Leber hereditary optic neuropathy (LHON) is a rare mitochondrial disorder primarily affecting young males, causing sequential visual loss due to optic nerve degeneration. LHON's unique maternally inherited trait, linked to mitochondrial DNA (mtDNA) point mutations, impacts complex I subunit genes, particularly m.11778G.A>MTND4, m.3460G.A>MT-ND1, and m.14484T.C>MT-ND6 mutations in about 90% of cases. Although these mutations are present, not all carriers manifest symptoms owing to variable tissue heteroplasmy. Genetic and environmental influences, X-linked genes, and immunological aspects contribute to the disease's varied onset and progression.

LHON typically initiates painlessly in one eye, progressing to the second eye within a year, leading to profound visual impairment, color vision deficits, and central scotomas. Although fundus examinations aid diagnosis, their absence doesn't rule out LHON. Recent advancements like optical coherence tomography (OCT) contribute to a better understanding and staging of the disease. Management includes lifestyle adjustments, vitamin supplements, and the use of idebenone in the subacute phase, aiming for vision recovery. However, most cases endure irreversible visual loss, necessitating ongoing supportive care and genetic counseling for affected families.