Spontaneous Visual Recovery After Acute Bilateral Optic Neuropathy Related to a New Opa1 Mutation in the Alternatively Spliced Exon 5b.

Abstract

Purpose:: Spontaneous recovery has been described in several types of non syndromic optic neuropathies, including Leber hereditary optic neuropathy with mutations in mitochondrial DNA, but not in dominant optic atrophy with mutations in OPA1.

Methods:: We screened LHON and OPA1 genes in one case of non syndromic acute optic neuropathy with spontaneous visual recovery and analysed skin fibroblasts from this patient and his father a healthy carrier.

Results:: We report a new singular OPA1 mutation in a 23 year-old patient that presented an acute visual loss that later reverted to almost normal vision. The mutation c.740G>A is the first mutation reported in the alternative exon 5b and induces R247H substitution that probably affects the ability of the corresponding domain to form a coiled-coil structure. Patient skin fibroblasts showed an abnormal mitochondrial tubular structure, a highly increased susceptibility to apoptotic stimulus, but no deficiency in mitochondrial DNA content or in membrane potential. Similar phenotypes were observed in fibroblasts from the father of this patient who was a healthy carrier of the mutation.

Conclusions:: This report emphasizes the interconnections between the clinical presentations of optic neuropathies associated to OPA1 and mitochondrial DNA mutations, and should orientate genetic diagnosis towards sequencing of OPA1 exon 5b in cases of patients showing an acute visual loss with a genealogy incompatible with maternal transmission.

Keywords: neuro-ophthalmology: optic nerve • mitochondria • gene screening