Abstract- Autism spectrum disorder (ASD) is a neurological disorder with unknown causes; it may be genes and environment factor, that both play important role in development of autism. It can be diagnosed at any age, so it is a developmental disorder which affects person act, interact, behavior, and communication with others. Autism is called a spectrum disorder because has a range of symptoms different from person to other and each one has his own world. It is a lifelong disorder where the symptoms of autism begin early in childhood; usually appears in the first two years of life and lasts with person's life. There is no standard treatment of autism, but detecting it early will lead to better results. At this research we will study the biological basis of autism and how can be detected at early stages prior to age 12 months. This study will depend on examining the gene expression pattern, early bio-markers related to early brain overgrowth, and cerebellar development to the infants less than 12 months to detect the autism early and help to control the symptoms. Early treatment of autism will improve the brain structure, function and behavior. Also, it will prevent the person from having autism all his life.
Keywords: Autism, autism spectrum disorder, bio-markers, gene expression, spectrum disorder, early detection.