Fragile X and Related Autism Spectrum Disorders, Volume 172 in the International Review on Neurobiology series, highlights new advances in the field, with this new volume presenting interesting chapters on The dopamine hypothesis of Autism Spectrum Disorder: a comprehensive analysis of the evidence, A Review of the Use of Psychotropic Medication to Address Challenging Behavior in Neurodevelopmental Disorders, Lipid metabolism alterations in fragile X syndrome and other neurodevelopmental disorders, Genesis, modelling and methodological remedies to autism heterogeneity, Toward an Understanding of the Role of the Exposome on Fragile X Phenotypes, Glial-mediated dysregulation of neurodevelopment in Fragile X Syndrome, and more.