Leber's hereditary optic neuropathy mutations associated with infantile-onset myoclonic epilepsy
1Division of Child and Adolescent Neurology, Department of Pediatrics, and Children's Learning Institute, University of Texas Health Science Center, Houston, TX 77030, USA. Richard.e.frye@uth.tmc.edu
Insights
Infantile myoclonic epilepsy can stem from mitochondrial DNA mutations, not just SCN1A gene mutations. This finding is crucial for diagnosing severe epilepsy syndromes in infants, especially when typical genetic markers are absent.
Area of Science:
- Neurology
- Genetics
- Mitochondrial Biology
Background:
- Epilepsy syndromes in infancy, particularly those with myoclonic seizures, are linked to significant developmental and neurological issues.
- Dravet syndrome, a severe form of infantile epilepsy, is often associated with fever-induced seizures and SCN1A gene mutations in a subset of patients.
Observation:
- Two children presented with clinical characteristics of severe myoclonic epilepsy of infancy.
- Genetic analysis revealed no mutations in the SCN1A gene in these patients.
Findings:
- The children were found to have mitochondrial DNA mutations linked to Leber's hereditary optic neuropathy.
- Both patients exhibited signs of mitochondrial dysfunction, drug-resistant epilepsy, and non-neurological system impairments.
Implications:
- Mitochondrial DNA mutations, particularly those related to Leber's hereditary optic neuropathy, should be investigated in infants with myoclonic epilepsy.
- This broadens the diagnostic scope for severe infantile epilepsy beyond SCN1A gene mutations.
- Identifying mitochondrial causes can guide targeted therapeutic strategies for affected children.
Abstract:
Epilepsy syndromes with onset in the first year of life, especially when they include myoclonic features, have special significance since they are associated with long-term developmental and neurological abnormalities. Dravet's severe myoclonic epilepsy in infancy is especially interesting as it is associated with fever-provoked seizures and mutations in the alpha subunit of the sodium channel (SCN1A) in about one-third of the cases. Here, we report 2 children who had clinical features of severe myoclonic epilepsy of infancy without mutations in the SCN1A gene who were found to have mitochondrial DNA mutations associated with Leber's hereditary optic neuropathy. These 2 children demonstrated markers of mitochondrial dysfunction, drug-resistant epilepsy, and dysfunction of nonneurological systems. These cases demonstrate that mitochondrial DNA mutations, especially those associated with Leber's hereditary optic neuropathy, should be considered in cases of myclonic epilepsy starting in infancy, especially when mutations in the SCN1A gene are not found.
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