The genetic basis of Autism spectrum disorder

Abstract

Autism spectrum disorder (ASD) is multifactorial and complex condition, with a marked genetic influence, as evidenced by the high heritability (around 80—90%). Additionally, both common and rare genetic variants have an influence on the etiology and development. Several genetic syndromes are described in ASD, and they are present in approximately 10% of cases. Different genetic approaches are described in studies with ASD samples. Linkage studies mainly identify regions in chromosomes 2 and 7 which are involved in ASD. Genetic association studies, which aim to identify genes or genomic regions influencing ASD, involve the analysis of candidate genes or genome scan. The genes analyzed in these studies encode components related to neurotransmitter metabolism, neural migration, neuronal cell adhesion, apoptosis, and cell proliferation. Other methodologies have been used to complement genetic investigations, for example, exome and copy number variation (CNV) studies. Epigenetic studies indicate an important environmental influence on these disorders. The genetic evaluation of all patients with ASD is now required due to recent advances in knowledge regarding the genetic factors involved in the etiology of autism. Definitions of key terms and concepts used throughout this chapter are presented in Fig.3.1.