Thousands of microvilli form a structure called the brush border that is found on the apical surface of some epithelial cells, such as the small intestines. (Microvilli should not be confused with intestinal villi, which are made of many cells.
Autism spectrum disorder has no single known cause. Given the complexity of the disorder, and the fact that symptoms and severity vary, there are probably many causes. Both genetics and environment may play a role. 1  Genetic problems. 2  Several different genes appear to be involved in autism spectrum disorder.
Causes and Risk Factors for Aspergerâs Syndrome There is no one single cause for the development of autism spectrum disorders, including Aspergerâs syndrome. However, when considering the complexity of the disorder and the fact that symptom severity varies, there are likely many different causes. Some current theories include: