The Developmental Synaptopathies Consortium is composed of a group of medical centers throughout the US studying three related rare genetic syndromes that often cause autism spectrum disorder and intellectual disability. Autism spectrum disorder and intellectual disability (ASD/ID) are severe neurodevelopmental conditions with early childhood onset. Advances in genetics have indicated that ASD/ID represent a spectrum of rare disorders. While both ASD and ID have a variety of known genetic causes, some of them have been shown to impair similar cellular pathways in the brain. The three conditions to be studied by the Consortium are tuberous sclerosis complex (caused by mutations in the TSC1 and TSC2 genes), Phelan-McDermid syndrome (caused by SHANK3 mutations) and PTEN Hamartoma Tumor Syndrome (caused by PTEN mutations). These three rare diseases seem to affect certain shared pathways influencing the development of brain connections, or synapses.