Overview in the etiopathogenesis of different phenotypes of autism

The purpose of this study was to determine the evolution of autism by characterization of the validated biomarkers implicated in the pathophysiology of this disease to help in the diagnosis and treatments of ASD children. This study was conducted on 90 autistic children aged 2-7 years old. These children were divided into two main groups; the atypical autism group of 30 children and the childhood autism group of 60 children. The childhood autism group then divided into two groups of 30 children according to the severity of the disorder to mild-moderate autism group and severe autism group. The study also included 30 healthy children served as a control group. All participants were subjected to full psychiatric examination and psychological investigations. Biochemical measurements (TNF-α, GABA, GSH in plasma, glutamate in serum, and hair mercury) were done. The autistic groups showed a highly significant difference in both CARS and Vineland scores, a highly significant increase in hair mercury and in plasma TNF-α, GABA and glutamate in serum versus control. Plasma GSH level and glutamate/ GABA ratio were significantly decreased in childhood autism group.The level of hair mercury, plasma TNF-α, serum glutamate and Glutamate/ GABA ratio were significantly decreased with the increased disease severity. While plasma GABA level was significantly increased with the increased disease severity. Conclusively, excessive burden on the developing brain with mercury plays the critical role in the etiology of ASD. Neuro inflammations have a protective role during acute inflammation and a destructive role in chronic inflammation. These key elements would affect the brain homeostasis which could most probably lead to the pathogenesis of autism.