Autism Spectrum Disorder

728 Words Feb 21st, 2018 3 Pages
ASD is not a single disorder, but rather a neurodevelopmental syndrome. (Autism Speaks)
Research shows that a combination of genetic and environmental factors leads to the abnormal brain development that underlies autism. The concordance rate for monozygotic twins is much higher than for dizygotic twins, roughly 2:1, indicating that there are both large genetic and environmental components. (Hallmayer 2011) The importance of environment is also demonstrated by the fact that fraternal twins have a considerably higher concordance rate than normal siblings, although non twin siblings are as genetically similar as fraternal twins. The marked rise in the reported incidence of autism (larger than can be attributed to increased recognition and reporting) also supports the idea that there is a large environmental component. (Cone 2009)
It is likely that multiple small factors, both environmental and genetic, make small contributions that ultimately lead to autism. For most cases of autism, a number of gene alleles (many of which are connected to various neurological problems) make a contribution to an individual being autistic. (NINDS, Wall) Support for this includes the high incidence of autism related symptoms in the relatives of individuals with autism.
(Constantino 2003) Moreover, half of the genes believed to be involved in…
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