AUTHOR=Wundrach Dean , Martinetti Luis E. , Stafford April M. , Bilinovich Stephanie M. , Angara Kartik , Prokop Jeremy W. , Crandall Shane R. , Vogt Daniel TITLE=A Human TSC1 Variant Screening Platform in Gabaergic Cortical Interneurons for Genotype to Phenotype Assessments JOURNAL=Frontiers in Molecular Neuroscience VOLUME=13 YEAR=2020 URL=https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2020.573409 DOI=10.3389/fnmol.2020.573409 ISSN=1662-5099 ABSTRACT=

The TSC1 and TSC2 genes are connected to multiple syndromes from Tuberous Sclerosis Complex (TSC) to autism spectrum disorder (ASD), with uncertainty if genetic variants cause all or subsets of phenotypes based on the location and type of change. For TSC1, few have addressed if non-TSC associated genetic variants have direct contributions to changes in neurological genotype-to-phenotype impacts, including elevated rates of ASD and seizures. Dominant variants cause TSC, yet TSC1 has many heritable variants not dominant for TSC that are poorly understood in neurological function, with some associated with ASD. Herein, we examined how missense variants in TSC1, R336W, T360N, T393I, S403L, and H732Y, impacted the development of cortical inhibitory interneurons, cell-types whose molecular, cellular, and physiological properties are altered after the loss of mouse TSC1. We found these variants complemented a known phenotype caused by loss of TSC1, increased cell size. However, distinct variants, particularly S403L showed deficits in complementing an increase in parvalbumin levels and exhibited smaller amplitude after hyperpolarizations. Overall, these data show that subtle phenotypes can be induced by some TSC1 missense variants and provide an in vivo system to assess TSC1 variants’ neurological impact better.