Oxidative stress in Rett syndrome.

The investigation of parameters that might influence the neurological evolution of Rett syndrome might also yield new information about its pathogenic mechanisms. Oxidative stress caused by oxygen free radicals is involved in the neuropathology of several neurodegenerative disorders, as well as in stroke and seizures. To evaluate the free radical metabolism in Rett syndrome, we measured red blood cell antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase) and plasma malondialdehyde, as lipid peroxidation marker in a group of patients with Rett syndrome. No significant differences were observed in erythrocyte glutathione peroxidase, glutathione reductase and catalase activities, between the Rett syndrome patients and the control group. Erythrocyte superoxide dismutase activities were significantly decreased in Rett syndrome patients (P<0.001) compared with the control group. Plasma malondialdehyde concentrations were significantly increased in Rett syndrome patients (P<0.001). An unbalanced nutritional status in Rett syndrome might explain the reduced enzyme activity found in these patients. Our results suggest that free radicals generated from oxidation reactions might contribute to the pathogenesis of Rett syndrome. The high levels of malondialdehyde reflect peroxidative damage of biomembranes that may contribute to progressive dementia, impaired motor function, behavioural changes, and seizures, in Rett syndrome. We found a probable relationship between the degree of oxidative stress and the severity of symptoms, which should be further investigated with a larger number of patients in different disease stages.