Serum levels of SOD and risk of autism spectrum disorder: A case‐control study

Abstract Background Autism is a severe developmental disorder with poorly understood etiology. This study examined the clinical significance of serum superoxide dismutase (SOD) level, a marker of oxidative stress, in children with autism spectrum disorder (ASD) and typically‐developing children between the ages of 2 and 6 years. Methods Ninety‐six children diagnosed with ASD and 96 sex and age matched typically‐developing children were assessed for serum levels of SOD at admission. S0D were assayed by colorimetry, and severity of ASD was evaluated with the Childhood Autism Rating Scale (CARS) Score. The influence of serum SOD levels on ASD was performed by conditional logistic regression analysis, which allows adjustment for confounding factors. Results The median serum SOD levels were significantly (P < 0.001) lower in children with ASD as compared to typically‐developing children [146 (IQR: 133–165) U/ml and 180 (168–199) U/ml, respectively]. Levels of SOD increased with decreasing severity of ASD as defined by the CARS score (r = −0.432, P < 0.0001). After adjusting for all other possible covariates, SOD remained can be seen as an independent indictor of ASD with an adjusted odds ratio (OR) of 0.955 (95% confidence interval [CI], 0.942–0.969; P < 0.001). Based on the receiver operating characteristic (ROC) curve, the optimal cutoff value of serum level of SOD as an indicator for auxiliary diagnosis of ASD was projected to be 160U/ml, which yielded a sensitivity of 84.7% and a specificity of 71.4%, with the area under the curve at 0.811 (95%CI, 0.747–0.874). Conclusions Our data suggests that the decreased serum SOD levels could be implicated in the pathophysiology and progression of autism in Chinese children and can be used as an independent risk indicator of ASD.