Genetic diagnosis of severe myoclonic epilepsy of infancy (Dravet syndrome) with SCN1A mutations in the Hong Kong Chinese patients.

Epilepsy is a clinically and genetically heterogeneous group of disorders. The advent of molecular genetics brings unprecedented advancement in diagnostic molecular pathology and reduces over-reliance on traditional clinical classification. Severe myoclonic epilepsy of infancy or Dravet syndrome is a catastrophic infantile-onset epilepsy. We report two unrelated Hong Kong Chinese patients with this condition presenting with febrile seizures, epilepsy with different semiologies, psychomotor retardation, and recurrent status epilepticus. Two different mutations were characterised, viz NM_001165963.1: c.680T>G; NP_001159435.1: p.I227S and NM_001165963.1: c.3953T>G; NP_001159435.1: p.L1318R (novel). Genetic characterisation conveys a definitive diagnosis and is important from the perspective of selecting anti-epileptic drug therapy and genetic counselling.