Anti-SPTAN1 monoclonal antibody, clone FQS4941

Recent progress in genetic analysis reveals that a significant proportion of cryptogenic epileptic encephalopathies are single-gene disorders. Mutations in numerous genes for early-onset epileptic encephalopathies have been rapidly identified, including in SPTAN1, which encodes alpha-II spectrin. The aim of this review is to delineate SPTAN1 encephalopathy as a distinct clinical syndrome. To date, a total of seven epileptic patients with four different in-frame SPTAN1 mutations have been identified. The major clinical features of SPTAN1 mutations include epileptic encephalopathy with hypsarrhythmia, no visual attention, acquired microcephaly, spastic quadriplegia and severe intellectual disability. Brainstem and cerebellar atrophy and cerebral hypomyelination, as observed by magnetic resonance imaging, are specific hallmarks of this condition. A milder variant is characterized by generalized epilepsy with pontocerebellar atrophy. Only in-frame SPTAN1 mutations in the last two spectrin repeats in the C-terminal region lead to dominant negative effects and these specific phenotypes. The last two spectrin repeats are required for alpha/beta spectrin heterodimer associations and the mutations can alter heterodimer formation between the two spectrins. From these data we suggest that SPTAN1 encephalopathy is a distinct clinical syndrome owing to specific SPTAN1 mutations. It is important that this syndrome is recognized by pediatric neurologists to enable proper diagnostic work-up for patients.

A 1-year-old male began suffering from West syndrome at 3 months of age, when electroencephalography revealed hypsarrhythmia accompanied by a periodic, brief suppression phase. The administration of adrenocorticotropic hormone was partially effective for stopping the condition, and the seizure type evolved into brief tonic seizures at 6 months. Thereafter, progressive atrophy of the brain became evident by 9 months of age, predominantly at the brainstem and cerebellum. Severe hypomyelination of the cerebral white matter was revealed at the age of 1 year, and a de novo heterozygous mutation in the SPTAN1 gene was confirmed. The patient showed severely impaired psychomotor development, and had gained no visual attention. These findings contribute to the characterization of this recently established entity and facilitate the identification of further patients. (C) 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.