A Novel SCN1A Mutation: A Case Report

Dravet syndrome (DS) is characterized by severe infant-onset myoclonic epilepsy with delayed psychomotor development and increased premature mortality. The seizures triggered by fire have been gradually decreased over time, and finally they start to occur without fever at the age of 2-3 years. Along with its initiation of myoclonic seizures in the early period, other types such as atypical absence, versive, and complex partial seizures occur between 1 and 4 years of age.

A 3-year-old male patient with refractory epilepsy and neuromotor developmental retardation was admitted to our clinic. The patient initially had seizures in the afebrile period, when he was 4 months old, and he had a total of five seizures by the age of 1 year. Neuromotor developmental retardation developed over time in patients with normal neuromotor development in the early stages of his life. His cranial magnetic resonance imaging and metabolic test findings were normal. The SCN1A mutation was investigated, and a new variant mutation of SCN1A, homozygous (p.Y1599Ffs*19-c.4796delA) was detected. The patient's family was also screened and this new mutation was detected as heterozygous mutation. The patient had hepatomegaly. The etiology of hepatomegaly was investigated but no cause was found.

Variant mutations of DS should be kept in mind and diagnostic genetic testing should be done in patients with neuromotor developmental retardation starting with afebrile seizures. In DS, hepatomegaly is not an expected condition. Maybe this new mutation might have caused hepatomegaly.