Abnormalities of synaptogenesis in autism. Pathogenic and therapeutic implications

The social, language, and behavioural problems that occur with autism suggest that this syndrome affects a functionally diverse and widely distributed set of neural systems. To review the molecular pathways involved in synaptic growth, development, and stability of human synapses. We also examine the genes implicated in synaptogenesis which have been associated with autism. In particular, we highlight the role of these genes in synaptic cell adhesion, organization of presynaptic and postsynaptic specializations, growth signaling pathways, and endosomal function. Proper brain function requires stringent balance of excitatory and inhibitory synapse formation during neural circuit assembly. Mutation of genes that normally sculpt and maintain this balance results in severe dysfunction, causing neurodevelopmental disorders including autism, epilepsy, Angelman syndrome, fragile X syndrome, and Rett syndrome. Such mutations may result in defective architectural structuring of synaptic connections, molecular assembly of synapses and/or functional synaptogenesis. Increased knowledge of abnormal mechanisms of human synaptogenesis may lead to define different etio-pathogenic models of autism and to understand how far abnormal cell/synaptic growth and synaptic function could be reversed.