TEFM-related disease is a rare disorder of mitochondrial transcription. So far there are only 7 cases reported in the literature and it has an autosomal recessive mode of inheritance. The phenotype is very variable: some patients had a multisystem presentation ranging from a 1) rapid neonatal metabolic decompensation with severe lactic acidosis, hypoglycaemia, neurological impairment, liver failure and death at 1 month of age; 2) to severe, progressive epileptic encephalopathy with myoclonic jerks, psychomotor regression, vomiting, ptosis and fluctuating ophthalmoparesis leading to death at 17 months of age; and 3) a less severe phenotype in some individuals, who are ambulatory with slowly progressive developmental delay, autism spectrum disorder and mild intellectual disability, non-specific mild developmental delay and ataxia, with or without optic atrophy, fluctuating proximal muscle weakness, ophthalmoparesis and epilepsy. Features consistent with congenital myasthenic syndrome, responsive to salbutamol therapy, were reported in 2 individuals. Clinical features can be variable even within the same family.
TEFM