There is strong evidence of the changes in the gene contribute to the occurrence of autism. According to the National Institutes of Health, a family who has one child with autism has a 10-20 times greater chance to give birth to children with autism as well.
Research on twins found that if one child with autism, twin most likely have the same disorder.
In general, the experts identified 20 genes that cause autism spectrum disorders. The gene plays an important role in brain development, brain growth, and how brain cells communicate.
High pesticide exposure is also associated with the occurrence of autism. Some research found that pesticides will disrupt the function of genes in the central nervous system. According to Dr. Alice Mao, professor of psychiatry, the chemicals in pesticides impact on those who have talent autism.
Babies who are exposed to certain drugs while in the womb have a greater risk of autism. These drugs include valproic and thalidomide. Thalidomide is a drug older generation used to overcome the symptoms of nausea and vomiting during pregnancy, anxiety, and insomnia.
Drug thalidomide itself has been banned in America because of the many reports of babies born with disabilities. However, these drugs are prescribed to address skin disorders and cancer therapy. Meanwhile, valproic acid is a drug used for patients with mood disorders and bipolar disorder.
4. Age parent
The older age of parents when a child, the higher the risk the child suffering from autism. The study, published in 2010 found that women aged 40 years had a 50 percent risk of having a child with autism compared with women aged 20-29 years.
"It is not known with certainty the relationship age of parents with autism. However, this is presumably because the occurrence of gene mutation factor," said Alycia Halladay, Director of Environmental Studies Research Autism Speaks.
5. Brain development
Certain areas in the brain, including cortex and cerebellum serebal responsible for the concentration, movement and mood regulation, related to autism. The imbalance of neurotransmitters, like dopamine and serotonin, the brain also associated with autism.