The Developmental Synaptopathies Consortium is composed of a group of 10 medical centers studying 3 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 3 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 disruption/mutations in the SHANK3 gene) and PTEN Hamartoma Tumor Syndrome (caused by mutations in the PTEN gene). These 3 rare diseases seem to affect certain shared pathways influencing the development of brain connections, or synapses.