Disease-related mutations in the mitochondrial methionyl-tRNA formyltransferase (MTFMT) gene encoding a critical enzyme for mitochondrial translation have been rarely reported and are described in association with Leigh syndrome and combined oxidative phosphorylation deficiency. Symptoms include developmental delay, followed by ataxia and spasticity manifesting at later stages. A man had a clinical picture suggestive of an acquired demyelinating disease. Brain magnetic resonance imaging (MRI) demonstrated extensive involvement of the optic nerves, cerebral white matter, brain stem, and spinal cord. Whole-exome sequencing detected a pathologic homozygous c.626C>T mutation in the MTFMT gene. These findings expand the clinical features and neuroimaging spectrum associated with MTFMT mutations to include a relapsing-remitting phenotype.
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