The goal of this chapter is to review the current knowledge of the genetic causes of
intellectual disability, focusing on alterations at the chromosomal and single gene level, with particular mention to the new technological developments, including array technologies and next-generation sequencing, which allowed an enormous increase in yield from genetic studies. The cellular and physiological pathways that seem to be most affected in intellectual
disability will also be addressed. Finally, a brief analysis of the contribution of the
genetically modified animal models for the study of the pathogenesis of intellectual
disability and for the development and testing of novel therapeutic approaches, with
unexpectedly good results, previously thought to be impossible to achieve. The chapter will close with some considerations on the relevance and future perspectives of genetic testing in patients with intellectual disability
