Early-onset encephalopathy with paroxysmal movement disorders and epileptic seizures without hemiplegic attacks: About three children with novel ATP1A3 mutations.

OBJECTIVE: Heterozygous mutations in the ATP1A3 gene are responsible for various neurological disorders, ranging from early-onset alternating hemiplegia of childhood to adult-onset dystonia-parkinsonism. Next generation sequencing allowed the description of other phenotypes, including early-onset epileptic encephalopathy in two patients. We report on three more patients carrying ATP1A3 mutations with a close phenotype and discuss the relationship of this phenotype to alternating hemiplegia of childhood. METHODS: The patients' DNA underwent next generation sequencing. A retrospective analysis of clinical case records is reported. RESULTS: Each of the three patients had an unreported heterozygous de novo sequence variant in ATP1A3. These patients shared a similar phenotype characterized by early-onset attacks of movement disorders, some of which proved to be epileptic, and severe developmental delay. (Hemi)plegic attacks had not been considered before genetic testing. SIGNIFICANCE: Together with the two previously reported cases, our patients confirm that ATP1A3 mutations are associated with a phenotype combining features of early-onset encephalopathy, epilepsy and dystonic fits, as in the most severe forms of alternating hemiplegia of childhood, but in which (hemi)plegic attacks are absent or only suspected retrospectively.

Cognitive functions in children with benign childhood epilepsy with centrotemporal spikes (BECTS).

Benign childhood epilepsy with centrotemporal spikes (BECTS) is regarded as a benign form of epilepsy because of its usually favorable outcome, in terms of seizures. Eighteen children with BECTS were studied in terms of neuropsychological and learning abilities: intellectual quotient, oral language (phonological production, naming skills, verbal fluency and syntactic comprehension), drawing and visuo-spatial skills, visual and selective attention, verbal and visuo-spatial memory, reading, numeracy and spelling. The mean IQ of the population was within the normal range, but individual results were heterogeneous. Verbal functions and memory were normal. In contrast, drawing and visuo-spatial skills, attention and visuo-spatial memory were significantly weak compared to the normal range for age. Reading, numeracy and/or spelling ability were significantly delayed by one academic year or more in ten of the children. In conclusion, despite its benign outcome in terms of epilepsy, BECTS can be accompanied by specific cognitive disorders and low academic achievement.

A novel mutation in the mitochondrial tRNA Asn gene associated with a lethal disease.

We describe a lethal mitochondrial disease in a 10-month-old child who presented with encephalomyopathy. Histochemical and electron microscopy examinations of skeletal muscle biopsy revealed abnormal mitochondria associated with a combined deficiency of complexes I and IV. After excluding mitochondrial DNA deletions and depletion, direct sequencing was used to screen for mutation in all transfer RNA (tRNA) genes. A T-to-C substitution at position 5693 in the tRNA(Asn) gene was found in blood and muscle. Microdissection of muscle biopsy and its analysis revealed the highest level of this mutation in cytochrome c oxidase (COX)-negative fibres. We suggest that this novel mutation would affect the anticodon loop structure of the tRNA(Asn) and cause a fatal mitochondrial disease.