Autism spectrum disorder (ASD) is a complex developmental condition that involves challenges in social interaction, nonverbal communication, speech, and restricted/repetitive behaviors. Autism is also called as “spectrum” disorder because there is a wide variation in the type and severity of symptoms people experience. Psychiatrists developed a systematic way of describing autism and related conditions. All of the conditions can be placed within a group of conditions called Autism Spectrum Disorders. ASD can be a lifelong disorder if diagnosis and treatment are delayed. Person’s symptoms and ability to function may improve with proper diagnosis and treatment. The symptoms, severity, and effects of ASD vary from person to person. Some people can navigate their world, whereas some others might have exceptional abilities, while others struggle to speak. It was first discovered in young children. Autism spectrum disorders (ASDs) affect about one child in 59, striking nearly four times as many boys as girls. Not all people with ASD show all behaviors, but most will show several.

There is a great range in characteristics of children with autism spectrum disorder — There is no single cause for ASD, and symptoms can be mild to very severe. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a guide by the American Psychiatric Association is used to diagnose mental disorders. People with ASD were discovered with following symptoms:
• Difficulty in communication and interaction with people
• Lack of contact with the eye
• High sensitivity to touches, sounds, smells, or sights that seem ordinary to other people
• Trouble pointing out things
• A narrow or intense range of interests in topics
• A repetitive and restricted patterns of behaviors, interests, or activities
• Trouble in understanding while other people talk, think, and feel.
• Restricted expressions
• Repetitive behaviors with restricted interests
• Trouble looking at or listening to other people
• Symptoms that hurt the person’s ability to function properly in school, work, and other areas of life
• Trouble adapting to changes in routine

Certain type of disorders was once thought to be separate conditions. Currently, they fall under the range of autism spectrum disorders. The disorders include:
• Asperger's syndrome: The children with Asperger's syndrome have trouble with language; they score in average or above-average range on intelligence tests having social problems, and a narrow scope of interests.
• Autistic disorder: This refers to problems with social interactions, communication.
• Childhood disintegrative disorder: The children with the disintegrative disorder have typical development for at least 2 years, then some or most of their communication and social skills get lost.
• Pervasive developmental disorder (PDD) or atypical autism: PDD diagnosis is used for severe and pervasive impairment in the development of reciprocal social interaction, nonverbal, verbal and communication skills.

Autism is considered a disorder of the brain and mainly runs in families. The exact underlying causes of its occurrence are unknown. Researchers found that causes for autism are likely to be genetic, bio-chemical, metabolic, and neurological. New research suggests that the peripheral nervous system also plays a role in autism. According to few other scientists the environmental factors are also involved.

Diagnosis of ASD is found difficult since there are no specific medical or clinical tests. Doctors usually look at the child’s behavior and development to make a proper diagnosis. There is no cure for autism. There are two main types of treatments: Behavioral and communication therapy to help with structure and organization. Applied Behavior Analysis (ABA) promotes positive behavior discouraging negative behavior. ASD can be a minor disorder that require full-time care under special facility. Forward genetics has been used for decades to search for mutations that cause autism. It induces genetic mutations in mice followed by screening for certain phenotypes and finally identifying the causative mutation of all genetic material of an organism. Biomarkers in human sperm have been identified that can indicate a propensity to father children with autism spectrum disorder. Early diagnosis and treatment are the ways by which autism could receive the needed help.