RT Book, Section A1 Kandel, Eric R. A1 Koester, John D. A1 Mack, Sarah H. A1 Siegelbaum, Steven A. SR Print(0) ID 1193101151 T1 Disorders Affecting Social Cognition: Autism Spectrum Disorder T2 Principles of Neural Science, 6e YR 2021 FD 2021 PB McGraw Hill PP New York, NY SN 9781259642234 LK neurology.mhmedical.com/content.aspx?aid=1193101151 RD 2024/03/28 AB MENTAL RETARDATION, now referred to widely as intellectual disability, is currently defined as having an IQ below 70 accompanied by marked deficits in adaptive functioning. Both terms have been broadly used to label a variety of cognitive impairments linked to prenatal or early postnatal brain abnormalities. For decades, subsets of individuals with rare intellectual disability syndromes, such as Rett syndrome or fragile X syndrome, have been characterized by their genetic etiologies. We are now beginning to elucidate the complex genetics of more prevalent neurodevelopmental disorders without distinct physical features that distinguish them, including so-called idiopathic or nonsyndromic forms of autism spectrum disorder (ASD). The combination of insights resulting from the intensive study of rare genetic syndromes coupled with successes in unraveling the genetics underlying idiopathic ASD has transformed our understanding of normal and pathological development of the human brain.