DNAJC30 Mutation in a Patient with Coexisting Leber's Hereditary Optic Neuropathy and Multiple Sclerosis (Harding's Syndrome): A Case Report.

Introduction: Patients with Leber's hereditary optic neuropathy (LHON) have a higher risk of developing multiple sclerosis (MS) than the general population. The coexistence of LHON and MS, also known as Harding's syndrome complicates the diagnosis of optic neuropathy, particularly when the underlying genetic mutation is a rare cause of LHON like DNAJC30.

Case presentation: We present a 26-year-old woman with progressive, sequential, painless, bilateral visual loss which was unresponsive to steroids, and two temporally distinct episodes of neurological disturbance suggestive of central nervous system demyelination. Thorough investigations including serological tests ruled out other causes, including negative neuromyelitis optica and myelin oligodendrocyte protein (MOG) antibodies and nutritional deficiencies. MRI detected areas of demyelination within the spinal cord and brain (infratentorial and periventricular areas). After genetic analysis revealing c.152A>G (p.Tyr51Cys) mutation at the DNAJC30 gene, LHON was suggested. She was prescribed with idebenone and her visual acuity resolved to normal at 4-year follow-up.

Conclusion: This case further expands the clinical presentations of DNAJC30-related LHON and underscores the importance of considering LHON in patients with demyelinating syndrome presenting with severe bilateral visual loss and presumed optic neuritis unresponsive to steroids.