Testing and counselling in inherited optic neuropathies

Purpose Inherited optic neuropathies are a diverse group of conditions presenting with mild to severe visual loss, colour vision deficits, central/ paracentral visual field defects, optic disc pallor and in many cases a positive family history. Modes of inheritance are dominant, recessive, X‐linked and mitochondrial. The absence of a family history does not exclude this diagnosis as there are many apparently new mutations and sporadic cases. Examination of first‐degree relatives may be essential if family history is in doubt. All of these conditions are untreatable but referral for genetic counselling, molecular diagnosis, low vision aids, school assistance and blindness registration may be of benefit to the patient and their family. Methods Autosomal dominant optic atrophy (ADOA) and Leber’s hereditary optic neuropathy (LHON) are the most common of these conditions. ADOA typically presents in mid to late childhood, with an insidious bilateral, symmetrical mild to moderate visual acuity loss, accompanied by dyschromatopsia, central/ centro‐caecal field defect and optic disc pallor. LHON typically presents in early adult life with a sudden, asynchronous, consecutive, catastrophic loss of central vision progressing rapidly to profound visual loss. Visual recovery is most unusual. Results At least three genes for dominantly inherited optic atrophy have been mapped (OPA1, OPA4 and OPA5), of which the gene has been identified in one (OPA1). A gene for recessive optic atrophy (OPA3) has also been identified. X‐linked optic atrophy (OPA2) has been mapped but to date no gene has been identified. Mutations in mitochondrial DNA have been identified in Leber's hereditary optic neuropathy. Conclusion Testing and counselling in the primary inherited optic neuropathies has positive benefits.