MEPAN syndrome

Mitochondrial enoyl reductase protein-associated neurodegeneration, known as MEPAN syndrome, is a rare inherited mitochondrial metabolic disorder. It usually presents in early childhood with dystonia, sometimes with chorea or ataxia, followed by progressive speech difficulty, optic atrophy and abnormal signals in the basal ganglia on MRI; a later-onset form with a Leber-like optic neuropathy has also been reported. It is autosomal recessive and results from pathogenic variants in the MECR gene, which encodes the enzyme that performs the last step of mitochondrial fatty acid synthesis. Diagnosis is confirmed by genetic testing, no curative treatment exists, and care focuses on managing dystonia, speech and vision. The disorder was first described by Heimer and colleagues in 2016.