Causes of autism: Metabolic disorders: congenital metabolic disorders such as phenylketonuria cause dysfunction and impairment of brain cells, which can affect the function of neural messaging in the brain and cause autism. Genetic factors: In 20% of autistic people, his family can be found with intelligence deficiency, delayed language development and similar autism. In addition, about 10% of boys with autism have chromosomal fragility disorder. Viral infection during pregnancy: A woman may suffer from a measles or influenza virus infection during pregnancy, which can cause autism by damaging the fetus’ brain development. Genetic factors: In 20% of people with autism, his family can be found with intelligence deficits, delayed language development and similar autism. In addition, about 10% of boys with autism have chromosomal fragility disorder. Brain injury: Factors including underdevelopment of the brain due to factors such as distress miscarriage during pregnancy, premature birth, obstructed labor, neonatal brain injury during delivery, and brain injury due to diseases such as encephalitis and meningitis in the infant may increase the chance of autism. There are of course other reasons for this, but none of them are definitive.