How children develop autism

Hettinger, J.; Liu, X. & Holden, J. (2007). "The G22A Polymorphism of the ADA Gene and Susceptibility to Autism Spectrum Disorders." Journal of autism development disorders, 38, pp. 14-9.

Noting the apparent relationship between problems in the metabolism of purine in certain individuals and the apparent role this plays in causing some autism cases, the researchers in this study tested certain alleles that have an affect on the metabolism of purine in an attempt to determine with more accuracy and reliability exactly what effect, if any, these congenital differences actually have on the development of autism. Before going directly into the process and findings/results of their study, the authors provide a background to the issue of autism and autism spectrum disorders, noting that there seems to be strong evidence of a genetic basis for the disease, but that finding the specific alleles responsible for the disorders has been difficult for two primary reasons: first, because there is a great deal of genetic and phenotypic variability in those with autism spectrum disorders, and second because there are likely many different alleles that can affect susceptibility to the disorder (Hettinger et al. 2007).

Regardless of the nebulous causes of autism spectrum disorders, the pathophysiology of the disease is generally agreed on to consist of certain neurotransmitter impairments, and/or disruptions of normal brain and central nervous system development (Hettinger et al. 2007). Certain case studies suggest that disruptions in the pathway concerning purine metabolism can have a detrimental effect on the development of other pathways in the central nervous system, possibly causing autism spectrum disorders (Hettinger et al. 2007). These case studies do not provide enough evidence by themselves that purine metabolism can be implicated in autism development, however.

In order to make an actual determination as to the relationship between purine metabolism and autism spectrum disorders, this research involved testing a gene known to affect purine metabolism and that therefore had a possible connection to causing autism (Hettinger et al. 2007). Specifically, the researchers identified the adenosine deaminase gene as the possible culprit for some cases of autism spectrum disorder linked to urine metabolism, as other issues with this gene develop similar metabolic and construction problems with other proteins and enzymes (Hettinger et al. 2007). Previous studies had noticed some correlation in sub-standard operation of this gene and certain cases and types of autism spectrum disorder, though there was not enough evidence to establish a causal relationship (Hettinger et al. 2007). This study was one of the first to directly examine the gene and its relationship to autism (Hettinger et al. 2007).