While several genetics studies are increasing the list of human genes implicated in autism, few studies can actually throw their impact on human neurons and their relevance to autism. This is the first report of a human stem cell model for sporadic (non-syndromic) autism. Here, we revealed a new gene (TRPC6) implicated in autism pre-disposition. Using multiple models, we showed that TRPC6 is important for neuronal homeostasis. Moreover, the gene is regulated by MeCP2 (the gene mutated in Rett syndrome), revealing common molecular pathways shared by different types of autism. The defects in neurons could be rescued by IGF-1, current in clinical trials for Rett syndrome. Moreover, we were able to test hyperforin, the active principle found in St. John’s Wort, to stimulate TRPC6 and rescue neuronal defects in a patient carrying mutation in one copy of the TRPC6 gene.