MEGDEL Syndrome: Expanding the Phenotype and New Mutations

3-MEthylGlutaconic aciduria, Deafness, Encephalopathy, neuroradiological evidence of Leigh-like disease (MEGDEL syndrome) was initially described in four children with additional features of defective oxidative phosphorylation. Loss of functional variants in the SERAC1 gene was later reported in relation with this disorder of phospholipid remodeling. We describe a girl born after a pregnancy complicated by intrauterine growth retardation. In the neonatal period, she presented hypotonia, lethargy, weak reflexes, transient hypoglycemia, and elevated transaminases. Magnetic resonance imaging (MRI) performed at 12 days of life showed bilateral basal ganglia alterations suggestive of Leigh syndrome. She progressed with failure to thrive, severe delay of developmental milestones, axial hypotonia, spastic tetraparesis and dystonic movements. Investigations disclosed hyperlactacidemia, and the urinary organic acids revealed high levels mainly of 3-methylglutaconic acid. Muscle biopsy showed decreased activity of several complexes of the respiratory chain. Compound heterozygosity for two previously unreported variants in SERAC1 leads to the diagnosis of MEGDEL syndrome. Unlike other patients, this child presents very early MRI alterations and manifests no deafness.