Neurological disorders are complex in nature and often the least understood. Given the recent boom in imaging technology and other diagnostic methods, it is now possible to see more clearly into the scope of neurological development and accurately determine the etiology of these diseases. One of such disorders is Autism; a multifactorial condition impairing normal brain development. It affects many aspects of development, including social behavior, cognitive ability and communication skills1 and is commonly diagnosed in children before the age of three1. The symptoms of this condition can vary greatly between individuals; hence its classification as a spectrum disorder. Asperger syndrome, Rett syndrome and pervasive developmental disorder are all within this spectrum, characterized by varying extents of social and communicative difficulties2.
Autism is a disorder that is increasing in prevalence1, and due to its multifaceted nature, there are still numerous discoveries yet to be made in this field. If the respective roles of the environment and genetics are better understood, then effective treatments can be created that get to the root of the disorder, an example possibly being an increase in gene therapy research as a new means of treatment. This paper serves to examine the basis of Autism, in terms of the contributing factors and to uncover whether or not it is a primarily genetic disorder.
II. Evidence for the “yes” side:
Family Studies suggest that Autism is hereditary3. One study involved collecting data on 943, 664 children under the age of 10 for the duration of 7 years, and it was found that 818 of them developed autism3. Children who have siblings affected with autism have a risk that is 22 times higher than those without affected siblings or a family history3, indicating that it is inherited. Due to the heritability of Autism, it has a strong genetic component.
Mutations that occur during transcription are also linked to the expression of genes associated with Autism Spectrum Disorder. ASD candidate genes are genes normally related to synapse function, but when the enzyme topoisomerase is inhibited, the genes are not fully expressed4, factoring into the phenotypic expression of Autism. The individuals studied who were affected by ASD had a numerous amount of mutated genes relating to transcription function4. This result illustrates the relationship between transcription and the phenotypic expression of autism.
Twin Studies also show that there is a strong genetic influence in autistics.
In a study of 44 sets of twins, there was a high concordance rate of autism and other disorders on the ASD spectrum for monozygotic twins (92%)5. This suggests that the genetic similarity between MZ twins influences their risk of expressing Autism. Dizygotic twins however, had a much lower concordance5, supporting the hypothesis that there is a correlation between genetic similarity and Autism risk. According to the study,...