Autism spectrum disorder (ASD) is a developmental disability that is caused by differences in the brain. Studies suggest that ASD could be the result of alterations in normal brain growth very early in development, which can be caused by defects in genes that control brain development and regulate the way brain cells communicate with each other. It is also more common in children who are born prematurely. Research suggests that autism develops from a combination of genetic and non-genetic or environmental influences.
In a minority of cases, there are very clear genetic abnormalities that cause autism, while in other cases, genetic differences are more complex and have not yet been discovered. Some people with ASD have a known difference, such as a genetic condition, while other causes are not yet known. Scientists believe that there are multiple causes of ASD that work together to change the most common ways in which people develop. The first twin autism study was conducted in 1977 on 11 identical twins and ten fraternal twins across Britain, where at least one of the twins had autism.
This study showed that the number of fraternal twins (5-20%) also represents the possibility that a couple who already has a child with autism will have a second child with autism (known as the “risk of recurrence”). To identify small fragments of DNA that may be related to the development of autism among so many base pairs, scientists need to study a large number of people with autism. The first genes that were definitively shown to contribute to the risk of autism were found in the early 1990s by researchers who analyzed gender-specific forms of autism caused by mutations in the X chromosome. This refers to the differences in genes that are also found in many people who do not have autism and who by themselves are not enough to cause autism.
The triple viral vaccine as a cause of autism is one of the most debated hypotheses about the origins of autism. Public awareness of the signs of autism and new screening tools have facilitated the early identification of autism. While there is no cure for ASD, intensive and early treatment can make a big difference in the lives of many children. The Autism Society of America and other advocates have even proposed that April be designated as Autism Acceptance Month.