Autism spectrum disorders (ASDs) are a collection of neurodevelopmental conditions that are usually of prenatal origin and can be diagnosed in early childhood, when it is severe (Gillberg 2010). The prevalence of ASDs in the United States is currently 1 in 68 children (Centers for Disease Control and Prevention 2014). ASDs affect mainly males, with an estimated 4: 1 ratio between males and females, which might be partly related to hormonal involvement in the development of the disease (Lombardo et al. 2012). Although the etiology of ASDs is unknown, many theories support an interaction of environmental and genetic factors (Smalley et al. 1988). The genetic variants participated in ASDs and inherited from parents to affected individuals have been estimated to explain~ 40% of ASDs risk. De novo mutations in the patients are thought to contribute to 15–20% of cases (Hallmayer et al. 2011, Devlin and Scherer 2012). Despite the un‑success in identifying the candidate genes that are responsible for the most of ASDs cases, epigenetic dys‑regulation of genes necessary for normal brain development and growth and cognitive function and behavior are associated with the etiology of ASDs (Liu et al. 2011). Autism is the most severe symbol of a group of neurodevelopmental disabilities known as ASDs and was first described by Leo Kanner (Baird et al. 2006, Kanner 1968). Autism is a heterogeneous neurological disorder defined by three core behavior impairments–for example, fractions in verbal and nonverbal communication, deficits in social interaction, and severe stereotyped behaviors that appear after a period of relatively normal development (American Psychiatric Association 2000). Individuals with Idiopathic autism (IA) have major deficits in temporal information processing (TIP)(Szelag et al. 2004). It has been shown that the genes participated in the folate/homocysteine pathway may be the risk factors for autistic children. Methionine synthase (MTR), methylenetetrahydrofolate reductase (MTHFR), and methionine synthase reductase (MTRR) are key enzymes participated in the folate‑mediated one‑carbon metabolism, and involves in DNA synthesis, methylation, and repair (Xu et al. 2004). MTR is consisted of five important regions, including homocysteine (HCY)‑binding,