C9orf72 and Aicardi-Goutieres syndrome: Reverse transcriptase inhibitors that target the L1 protein have been tested in a clinical trial for the neurodevelopmental disorder Aicardi-Goutieres syndrome [35, 36] and trials are currently underway in C9orf72 expansion positive individuals with ALS or frontotemporal dementia and in individuals with progressive supranuclear palsy.