The surge in autism diagnoses in recent decades has led to curiosity surrounding the biological origins of the condition. Some communities, especially those in the United States, have attributed the perceived increase in people with autism to environmental factors such as vaccines. However, this theory has proven false and researchers have since declared that autism is not on the rise. It seems that diagnoses are simply increasing along with increased awareness of the disorder. Somewhat obscured by all of the back and forth caused by misinformation, one question has been consistently posed: Is autism genetic?
The Iffy Answer
The answer to this question appears to be a resounding… partially. Sources, like the CDC, are cautious of putting all of the blame on inheritance. They acknowledge that one is more likely to have a child with autism if they are related to someone with autism already but also revealed that there are, in fact, environmental factors that can alter someone’s chances of being diagnosed with the condition. These factors include prenatal exposure to air pollution and even maternal obesity.
In most cases, people with autism and their families will have to settle for the idea that the case or cases that affect them are caused by some complex combination of both genetic and environmental contributions. Though, partially because of the lack of answers for most autism cases, researchers have been exploring the human genome for more concrete causes. Important to this research is the idea that autism is polygenic, meaning that it results from the combined effect of many genes. However, variants of specific genes have been found to possibly increase the likelihood of autism. These genes include SNCAIP and SLFN5.
SNCAIP is a gene on the 5th chromosome that leads to the creation of a protein known to interact with another protein within the brain called Alpha-synuclein. The SNCAIP gene’s relation to this very important protein has implicated some versions of it as possible factors in the development of Parkinson’s disease. SLFN5 is located on the 17th chromosome and may be involved in cell differentiation, or the specialization of cells. The versions of these two genes and others that are associated with autism may be inherited from a parent or be the result of spontaneous mutations.
The More Concrete Information
Outside of the majority of cases, some people may find that other genetic conditions increased their chances of being diagnosed with autism. A condition known as fragile X syndrome, in which the gene FMR1 does not produce the brain-developing protein FMRP, is linked to autism. Along with Fragile X syndrome, there is also Down syndrome which is diagnosed when an individual has an extra 21st chromosome. While these conditions do not make up the entirety of the list of those associated with autism, they are two major ones that could increase its likelihood.
