Autism, Susceptibility To, X-Linked 1

A number sign (#) is used with this entry because X-linked autism-1 (AUTSX1) is associated with mutation in the NLGN3 (300336) gene.

Description

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; Risch et al., 1999). 'Autism spectrum disorder,' sometimes referred to as ASD, is a broader phenotype encompassing the less severe disorders Asperger syndrome (see ASPG1; 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). Genetic studies in autism often include family members with these less stringent diagnoses (Schellenberg et al., 2006).

For a discussion of genetic heterogeneity of autism, see 209850.

Mapping

Auranen et al. (2002) performed a 2-stage genomewide screen for autism-spectrum disorders in 38 Finnish families and found evidence for potential susceptibility loci on several chromosomes, including Xq. A maximum multipoint lod score (MLS) of 2.75 was obtained near marker DXS7132.

Shao et al. (2002) performed a 2-stage genomewide screen for autism in a total of 99 families and found evidence for susceptibility loci on chromosomes 2, 3, 7, 15, 19, and X. The locus on chromosome X yielded the highest multipoint MLS (greater than 2.0 at marker DXS6789).

Molecular Genetics

In a Swedish family in which 1 brother had typical autism and another had Asperger syndrome (ASPGX1; 300494), Jamain et al. (2003) identified a mutation in the NLGN3 gene (300336.0001), located at Xq13.