Focal motor epilepsy and segmental dystonia associated to mutation in the KCTN1 gene: case report

*Correspondence: [e-mail].

Abstract

Case Presentation: 11-year-old female patient, single child of non-consanguineous healthy parents. She had normal psychomotor development until 5 years old, when she started epileptic seizures during sleep, characterized as focal motor with good response to oxcarbazepine. At the age of 7, she manifested with dystonia in the upper limbs, worse on the left side and cervical region, controlled with the use of trihexyphenidyl combined with baclofen and diazepam. She also evolved with a learning disorder and attention deficit with low school performance. During the investigation, she performed an EEG which revealed signs of immaturity and video-EEG showing paroxysmal events without electrographic correspondence, with nonspecific findings. MRI of the brain was normal. A New Generation Sequencing genetic study using a multigene panel revealed a heterozygous mutation in the KCTN1 gene; which promotes the substitution of the amino acid glycine for serine at codon 288 (p.Gly288Ser), classified as pathogenic.

Discussion: KCNT1-related epilepsy is associated with two phenotypes - epilepsy of infancy with migrating focal seizures (EIMFS) with onset at 6 months of age associated with developmental regression and autonomic manifestations and autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) with childhood-onset epileptic seizures with normal EEG or low-incidence paroxysms, movement disorder with tonic phenomena and dystonia, in addition to psychiatric and learning disorders, similar to that presented by the patient. KCNT1 mutations were described in the literature associated with the ADNFLE phenotype with penetrance close to 80%, refractory epilepsy, severe intellectual deficit and higher frequency of psychiatric disorders compared to other genes correlated with the same phenotype.

Final Comments: The KCNT1 gene presents with atypical epileptic seizures with usually normal EEG and early dystonia. Identifying the mutation allows the conduction of the appropriate treatment in order to avoid the motor sequelae of dystonia and a worse cognitive decline without proper management. In addition, through diagnosis, the family can be informed about the disease and undergo genetic counseling.

Publication History

Article published online:
12 May 2025