Autoimmune Disorder and Autism

1.1 Diagnosis of ASD Autism (also known as classic autism or autism disorder) is a common neurodevelopmental disorder. Typically diagnosed before three years old, autistic children usually present with significant language delays, social and communication impairments, as well as abnormal repetitive and restrictive behaviors. Autism spectrum disorders (ASD) however, refers to a boarder definition of autism. Based on the severity of the clinical conditions, ASD is further divided into three subgroups namely autism (the most severe type of ASD), Asperger syndrome and pervasive developmental disorder – not otherwise specified (PDD-NOS; also called atypical autism) [1-3]. Of note, current diagnosis criteria of these disorders are based on behavior tests, no single biomarker has been clinically accepted, which mainly due to the difficulties for studying cellular and molecular etiology of ASD. First, subjects among different researches lack of comparability because of the diagnostic heterogeneity [4]. Second, the prevalence of ASD is relatively low therefore sample sizes are usually too small for statistical analysis. Third, comparing with other diseases, the young ages of the autistic subjects make biological study difficult. Forth, valid control groups require age-, gender-, IQand socioeconomic statusmatched developmentally normal subjects, which most studies failed to satisfy with [5].