SCN8A epileptic encephalopathy: literature review and own observation

Abstract

A genetic disease caused by pathogenetic nucleotide variants in the SCN8A gene (Sodium channel protein type 8 subunit alpha, also known as Nav1.6), encoding the α-subunit of the Na channel type 8, is included in the group of early epileptic encephalopathies. In most cases, this pathology is characterized by the development of polymorphic pharmacoresistant epileptic seizures over the first year of a child’s life, a lag in psychomotor development or regression, loss of skills. In some patients, seizures may appear during the first days of life, while in others they appear later (at the age of 2 to 7 months), against the background of a pronounced or slight developmental delay. Types of seizures may include generalized, tonic-clonic seizures, infantile spasms, absences and focal seizures. Other signs and symptoms of encephalopathy caused by mutations of the SCN8A gene may include low muscle tone (hypotension), high pain threshold, motor disorders (such as dystonia and ataxia), mild to severe mental retardation, sleep problems and autistic traits. In some people with SCN8A encephalopathy, various other pathological changes in the body have been reported, including hearing or vision impairment, scoliosis, and thermoregulation difficulties. The disease is inherited by an autosomal dominant type. To date, the disease in the OMIM system is referred to as «Developmental encephalopathy and epileptic encephalopathy type 13». Previously, the disease was called «Early infantile (infantile) epileptic encephalopathy, type 13». The serial number «13» indicates this form of early epileptic encephalopathy to be caused by a heterozygous mutation in the gene on the long arm of chromosome 12 in chromosome region 12q13.13. This report also presents a clinical description of a patient suffering from early infantile epileptic encephalopathy, type 13.