Establishment of isogenic iPSCs from an individual with SCN1A mutation mosaicism as a model for investigating neurocognitive impairment in Dravet syndrome

Abstract

Dravet syndrome (DS) is a severe childhood epilepsy typically caused by de novo dominant mutations in SCN1A. Although patients with DS frequently have neurocognitive abnormalities, the precise neural mechanisms responsible for their expression have not been elucidated. There are wide phenotypic differences among individuals with SCN1A mutations, suggesting that factors other than the SCN1A mutation modify the phenotype. Therefore, a well-controlled cellular model system is required to improve our understanding of the mechanisms underlying DS. Here we generated induced pluripotent stem cell (iPSC) lines from an individual with SCN1A mutation mosaicism, and separately cloned iPSC lines both with and without the SCN1A mutation. These clones theoretically have the same genetic backgrounds, except for the SCN1A gene, and should serve as an ideal pair for investigating the pathophysiology caused by SCN1A mutations. Quantitative reverse transcription-PCR and western blot analysis revealed higher tyrosine hydroxylase mRNA and protein expression levels in mutant neurons than in wild-type neurons. Moreover, dopamine concentrations in media collected from mutant neural cultures were higher than those from wild-type neural cultures. Our findings suggest that SCN1A mutation leads to changes in the dopamine system that may contribute to the behavioral abnormalities in DS.

Outcomes and comorbidities of SCN1A-related seizure disorders

“…This nonlinear relationship indicates that behavioral problems are not completely subject to an epileptic encephalopathy disease model, as previously suggested [19,44]. Recent research has shown that SCN1A variants could lead to changes in the dopamine system that may contribute to behavioral problems, irrespective of seizure activity [45]. This, together with the large impact of behavioral problems on HRQoL scores and the high number of families affected by it, calls for more attention regarding recognition of behavioral problems.…”

SCN1A/NaV1.1 channelopathies: Mechanisms in expression systems, animal models, and human iPSC models

“…Isogenic iPSC pairs are commonly generated by employing site‐specific nucleases for genome engineering aimed at introducing or correcting the disease mutation in an iPSC line of reference . Alternatively, a study sought to generate isogenic lines exploiting the generation of iPSCs from peripheral blood cells of the asymptomatic individual carrying a truncating SCN1A mutation in mosaicism and mother of two brothers with DS . Transgene‐free reprogramming of peripheral blood lymphocytes generated 11 iPSC clones, 2 of which harbored the SCN1A heterozygous mutation causing DS in her children, whereas the remaining clones were wild‐type.…”

Monoaminergic Mechanisms in Epilepsy May Offer Innovative Therapeutic Opportunity for Monoaminergic Multi-Target Drugs

“…Nevertheless, DA concentrations in media collected from neural cultures, derived from induced pluripotent stem cells from a patient with the Dravet syndrome, were higher than those from wild-type neural cultures (Maeda et al, 2016). …”