Dear Editor, Autism spectrum disorders (ASD) are complex neurodevelopmental disorders characteristic of core behavioral traits like restricted,repetitive behaviors and deficiency in social interactions.1 The prevalence of ASD has rapidly increased worldwide,rising from 1/149 in 2000,1/68 in 2012,and to ～1/40 in 2016 of children at the age of 3-17 in the United States.2 ASD prevalence was found to be associated with socioeconomic status (SES) as overpresented in high-income households,3 and to be significantly enriched in certain regions,e.g.,reaching up to 4.88％ in Florida.2 In the last decades,advances in genetic studies have led to unprecedented understanding of the genetic factors that were associated with ＜ 50％ of human ASD.Tens of thousands of genomic events or gene mutations were found in ASD patients.Among these genetic factors,many seemed to indeed play causal roles in ASD etiology as animals bearing some of ASD-associated mutations manifested autistic-like behaviors.4-7 Since genetic factors are usually SES independent and unlikely to change in every few years,non-genetic factors including changes in life styles,environmental factors and their complex interaction with genetic factors are believed to prominently contribute to the recent rapidly increasing ASD prevalence.4-6 However,their nature and mechanisms of action remain largely undetermined.
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