RÉSUMÉ
OBJECTIVE: To explore the clinical phenotype and genetic etiology of a child with Developmental epileptic encephalopathy type 104 (DEE 104). METHODS: A child who had presented at the Children's Medical Center of the Affiliated Hospital of Guangdong Medical University in February 2021 for recurrent seizures over 1 month was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and his parents were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. RESULTS: The child, a five-month-old male, had presented with frequent focal seizures with severe developmental retardation from infancy. Physical examination showed emaciation, microcephaly, oblique palpebral fissures, Stahl's ears, and hypotonia in the limbs. Electroencephalogram revealed multi-focal sharp waves, slow waves and slow spinal waves. Cranial magnetic resonance imaging revealed enlargement of bilateral lateral ventricles and the third ventricle, along with widening of brain sulci, fissure and cisterna. WES revealed that he had harbored a heterozygous c.2401C>T (p.His801Tyr) missense variant of the ATP6V0A1 gene. Sanger sequencing showed that both of his parents were of the wild type. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was predicted to be likely pathogenic (PS2+PM2_Supporting+PP3). The proband was diagnosed with DEE 104. Early treatment with sodium valproate has failed, but the child had become seizure free after the addition of levetiracetam and topiramate. He still had abnormal EEG discharges and severe psychomotor retardation. Combining our case and a review of literature, DEE104 is mainly caused by de novo heterozygous variants of the ATP6V0A1 gene with an autosomal dominant inheritance. The patients may show refractory epilepsy and severe global developmental delay from infancy. CONCLUSION: The c.2401C>T (p.His801Tyr) variant probably underlay the DEE104 in this child.