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FB2025_02
,
released April 17, 2025
This report describes general characteristics of autism spectrum disorder (ASD). ASD is a complex multifactorial disorder involving many genes; multiple loci that appear to confer susceptibility have been identified (see the OMIM phenotypic series, link in "Related Diseases" section). Environmental triggers may also play a role in development of ASD. Assessment of genetic contribution to ASD is a rapidly evolving field, with ongoing identification of additional susceptibility loci.
For susceptibility loci studied using Drosophila models, see the "Related Diseases" section below.
[updated Mar. 2017 by FlyBase; FBrf0222196]
[AUTISM](https://omim.org/entry/209850)
Autism, the prototypic pervasive developmental disorder (PDD), is usually apparent by 3 years of age. It is characterized by a triad of limited or absent verbal communication, a lack of reciprocal social interaction or responsiveness, and restricted, stereotypic, and ritualized patterns of interests and behavior (Bailey et al., 1996, pubmed:8655659; Risch et al., 1999, pubmed:10417292). 'Autism spectrum disorder,' sometimes referred to as ASD, is a broader phenotype encompassing the less severe disorders Asperger syndrome (MIM:608638) and pervasive developmental disorder, not otherwise specified (PDD-NOS). 'Broad autism phenotype' includes individuals with some symptoms of autism, but who do not meet the full criteria for autism or other disorders. Mental retardation coexists in approximately two-thirds of individuals with ASD, except for Asperger syndrome, in which mental retardation is conspicuously absent (Jones et al., 2008; pubmed:18698615). [from MIM:209850; 2017.03.18]
Although apparently not causative in the absence of genetic susceptibility, environmental triggers may play a role in development of autism (https://www.niehs.nih.gov/health/topics/conditions/autism/).
The body of research identifying genetic deletions and duplications, inherited and de novo, and rare and common variants in ASD is expansive. Evidence for genetic variants in the etiology of ASD includes genes involved in intellectual disability and neuropsychiatric disorders, common pathway genes and ASD-risk genes, multigenic contributions from rare or common variations, DNA mutations, and environmental effects on gene expression and/or protein function. Rare genetic risk factors, including those resulting in ASD-related syndromes (e.g. Fragile X), chromosomal abnormalities, and penetrant genes are estimated to contribute to ~20% of ASDs. At least 5% of non-syndromic, idiopathic, and primarily simplex ASD are caused by de novo copy-number variants. It is estimated that 400-1000 genes are likely to lead to a susceptibility to autism. (Masi et al. 2017 and references therein, pubmed:28213805.)
Autism is considered to be a complex multifactorial disorder involving many genes. Genetic studies in autism often include family members with these less stringent diagnoses (Schellenberg et al., 2006; pubmed:16880825). [from MIM:209850; 2017.03.18]