Causes of ASD (Autism Spectrum Disorder):

Genetic Risk factors: In case of twins if one is suffered from ASD than 30% to 40% more chances that other will be also suffered from ASD and In case of cabling 10% to 20% more chances to be suffered from ASD. ASD tend to occur more often in people who have certain genetic or chromosomal condition such as Fringlex Syndrome. No single genes are responsible for ASD rather multiple genes are involved in ASD.

Environmental causes: When maternal exposure to certain viruses such as measles, mumps, Rubella, herpes, syphilis, cytomegalic and chemicals such as thalidomide, valproic acid during pregnancy. Children born to older parents have a greater risk to get suffer from ASD. Cerebral dysgenesis (Abnormal development of the brain) is also caused by ASD. Inborn error of metabolism is also is the cause of ASD.