Autism Spectrum Disorders
Autism Spectrum Disorders
Autism Spectrum Disorders is a clinical description of the developmental disorders which are characterized by impaired language development, social development, and learning. According to NIMH estimates, 3.4 out of every 1000 children between 3-10 years of age have one of the disorders in the spectrum.
Children with ASD have extremely delayed development. Symptoms of this disorder usually start to appear between 12 to 36 months and consist of not reaching normal development benchmarks such as babbling by 12 months, speaking by 16 months, or a gradual loss of language or social skills. All children with ASD show deficits in social interactions, verbal and nonverbal communication. They may also show repetitive behaviors and interests, or aggressive behavior.
Three common patterns seen in the emergence of autistic symptoms are 1) early manifestation of symptoms, 2) almost normal development, then sudden loss of previously attained social, communicative, or motor skills, or 3) mild delays until approximately 2 years of age, followed by a developmental halt. Children with ASD who show early manifestation of symptoms do not necessarily have a worse outcome of the three subsets. Those who follow a pattern of regression appear to exhibit less autistic symptoms prior to onset of regression and worse outcomes afterward as compared to the children who follow the other two patterns of development. 15
Prior to the 1970's, many people thought Autism Spectrum Disorders were a result of psychological causes, such as having an aloof mothering style. However, during the 1980's people began to note that chromosomal disorders and rare syndromes often co-occurred with ASD. As a result, people began to suspect that ASD could have genetic underpinnings. These suspicions were confirmed when, after the development of the ADI-R and ADOS as diagnostic tools and other technical advances, the first candidate gene association and resequencing studies, followed by whole-genome linking studies were done in the late 1990's. These studies were used to identify loci of potential interest.
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