Myoclonic Epilepsy with Ragged-red Fibers with Intranuclear Inclusions

We herein report a case of myoclonic epilepsy with ragged-red fibers (MERRF) harboring a novel variant in mitochondrial cysteine transfer RNA (MT-TC). A 68-year-old woman presented with progressive myoclonic epilepsy with optic atrophy and peripheral neuropathy. A skin biopsy revealed p62-positive intranuclear inclusions. No mutations were found in the causative genes for diseases known to be related to intranuclear inclusions; however, a novel variant in MT-TC was found. The association between intranuclear inclusions and this newly identified MERRF-associated variant is unclear; however, the rare complication of intranuclear inclusions in a patient with typical MERRF symptoms should be noted for future studies.

Automated summary

We report a case of MERRF with a novel variant in MT-TC, characterized by progressive myoclonic epilepsy with optic atrophy and peripheral neuropathy. Intracellular inclusions were found in the skin biopsy, but no mutations were identified in known causative genes for diseases associated with intracellular inclusions. The association between these inclusions and the newly identified MERRF-associated variant remains unclear.