AUTISM SPECTRUM DISORDERS – ADVANCES IN MOLECULAR BIOLOGY
Keywords:Autism spectrum disorders, Autism, Chromosome, Locus, Gene
Autism spectrum disorders (ASD) are neurodevelopmental disorders that include behaviour, communicational and social interaction impairments. According to DSM-IV TR there are five ASDs in the category of pervasive developmental disorders: autistic disorder, Asperger Syndrome, pervasive developmental disorder not otherwise specified, childhood disintegrative disorder, and Rett syndrome. The prevalence of ASD varies from 10 per 10000 to 60 cases per 10 000 children, according to different epidemiological studies. A small number of individuals with ASD has a well defined aetiology, being this challenging for scientific purposes. Studies of twins and families have showed a high heritability of autistic disorder, nonetheless its genetic bases, as well as the identification of some genes or proteins that can be use to identify these disorders have not been completely clarified. According to the literature only a small percentage of subjects with ASDs have know aetiology, which has raised concern in the scientific community in the last decade. The ASDs have been associated with known genetic causes in 10-15% of the cases. Different genes and chromosomal regions (loci) potentially associated with ASDs have been described, being the chromosomal anomalies responsible for less than 10% of the autism cases. There are also some cytogenetic abnormalities in patients with autism described in the literature, namely the duplication of 15q11-q13, the deletion and duplication in the 16p11 band, and the deletion in the 22q13 region. The chromosomal regions are reviewed in detail in the present article, as it is our conviction that future research will clarify some of the complex genetic basis of ASDs. The cytogenetic anomalies of the locus 15q11-q13 are present in 1 -4% of the autism patients; it is reasonable to establish an association between the microdeletion in the sub-band 16p11.2 and the autism, and, in addition, the deletion and duplication in the chromosome 22q13.3 are potential risk factors to the ASDs.
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