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Infantile seizures are usually brief, but commonly recurrent, and strong consideration should be made for inpatient observation. Acute imaging with CT can alter management in a small but important number of infants. Due to the superior yield, strong consideration for MRI should be given for all infants, as primary generalized seizures are rare, and there is a high rate of cerebral dysgenesis.

Early infantile epileptic encephalopathy-9 (EIEE9) linked to mutations of the PCDH19 gene on the X chromosome was once thought to only affect females. Clinical features of the mutation include early onset of variable types and frequency of recurrent cluster of seizures, mild to profound intellectual disability, autistic traits, psychiatric features, and behavioral disturbances. PCDH19 pathogenic variants usually occur via an unusual X-linked pattern where heterozygous females are affected, but hemizygous males are asymptomatic. Somatic mosaic males for PCDH19 mutations are affected with EIEE9; since this discovery, four somatic mosaic males have been reported. We report the fifth confirmed male with somatic mosaicism of a novel pathogenic variant c.2147+2 T>C located in the splice site of Intron 1 of the PCDH19 gene, which continues to support that cellular interference is responsible for the pathogenic mechanism. The importance of our report is to provide significant knowledge about this rare cause of epilepsy in males, guide subsequent functional studies on males portraying an EIEE9 phenotype that have been potentially misdiagnosed, targeted therapeutic approaches, and further elucidation of this complex and interesting genetic disorder.

Dravet syndrome is a rare epileptic encephalopathy linked to mutations in SCN1A (neuronal sodium channel α1 subunit) and characterized by an onset in infancy with polymorphous seizure types and developmental decline. It was reported recently that a proportion of patients previously diagnosed with alleged vaccine encephalopathy might possess SCN1A mutations and clinical histories that enabled a diagnosis of Dravet syndrome, but these results have not been replicated. We present here the cases of 5 children who presented for epilepsy care with presumed parental diagnoses of alleged vaccine encephalopathy caused by pertussis vaccinations in infancy. Their conditions were all rediagnosed years later, with the support of genetic testing, as Dravet syndrome. We hope that these cases will raise awareness of Dravet syndrome among health care providers who care for children and adolescents and aid in earlier recognition and diagnosis.

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