The list of genes linked to autism is constantly evolving. Scientists estimate that hundreds of genes are linked to autism, many of which have yet to be identified. As researchers study more people with the condition, including SPARK participants, they learn more about the genetic risk factors.
Scientists discovered several years ago that so-called de novo mutations play an important role in autism genetics. This type of genetic change is not inherited from a person’s mom or dad. Instead, this type of genetic change is new in the person with autism.
To identify de novo changes, scientists need to study the person with autism as well as the person’s biological parents. De novo changes that are found in people with autism and not their unaffected siblings highlight genes for further study.
To figure out if the de novo change plays a role in autism, scientists must identify multiple people with autism with de novo changes in the same gene. As scientists identify more and more people with autism with de novo changes in the same gene, the evidence for that gene’s role in autism grows.
SPARK’s genetic analysis focuses on over 70 autism genes with strong evidence that links them to the condition. To make it onto SPARK’s list, a gene needs to be linked to autism in multiple independent studies and in multiple unrelated people. SPARK’s list will grow as additional genes meet these conditions. A committee made up of medical geneticists reviews the list every year.
Many of these genes haven’t yet been studied extensively. It's unclear how they raise risk of autism or whether they are linked to specific autism symptoms. One of SPARK’s goals is to help expand what we know about them. By finding more people with these genetic differences, scientists can learn more about what specific genes do. This information might aid development of new treatments or help target different treatments to specific groups.
For a more in-depth discussion of how scientists define novel autism genes, see this article from Spectrum, an independent news site funded by the Simons Foundation, SPARK’s parent organization.