Autism, Susceptibility To, 8

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, stereotypical, 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

In a group of 38 Finnish families in which a proband had autism, Auranen et al. (2002) found that approximately one-third of the probands had a first-degree relative with Asperger syndrome or developmental dysphagia. The authors defined this group as having 'autism spectrum disorders.' In 19 families with autism alone, the most significant evidence for linkage was found on chromosome 3q25-q27, with a maximum 2-point lod score of 3.16 with marker D3S3037. In another 18 families with autism and Asperger syndrome (see 608638), Auranen et al. (2002) found an increased lod score of 4.31 at the same marker (D3S3037).

Nomenclature

Auranen et al. (2002) referred to the locus for autism susceptibility on 3q25-q27 as 'AUTS2.' This symbol had also been used to refer to a gene on chromosome 7q11 (KIAA0442; 607270).