Advances in the genetics and neuropathology of tuberous sclerosis complex: edging closer to targeted therapy.

Tuberous sclerosis complex is a rare genetic disease associated with mutations in the TSC1 or TSC2 genes, which cause overactivation of the mTOR complex. In the past 5 years, understanding has increased of the cellular consequences of TSC1 and TSC2 genetic variants and the mTORC1 overactivation in neurons and glial cells and their contribution to network dysfunction. Infants and young children (aged 1-5 years) with tuberous sclerosis complex might now benefit from early assessment of gene variant status and mosaicism. In the past 5 years, substantial advances have also been made in our understanding of mTOR-related neuropathology and the molecular aspects of both epileptogenesis and co-occurring neurodevelopmental disorders. Many potential disease-modifying strategies have been identified, including developments in targeted therapies based on molecular findings in epilepsy. Reliable EEG and MRI biomarkers are now available to identify, at a younger age than previously possible, infants with tuberous sclerosis complex who are at risk of epilepsy, autism, and developmental delay. Vigabatrin has been used successfully as a treatment in infants with tuberous sclerosis complex who showed abnormalities on EEG before seizure onset. The scope for mitigation of tuberous sclerosis complex-associated symptoms has expanded, including the use of mTOR inhibitors such as sirolimus and everolimus. Close cooperation between clinical and basic neuroscientists has provided new opportunities for future advances.