While the number of autism diagnoses remains on the rise due to improved testing that makes it easier for doctors and therapists to identify autism at a younger age, one long-standing trend in autism diagnoses has remained unchanged: Men are more likely to have autism than women. In fact, males are four times more likely to be diagnosed with autism spectrum disorder.
As a result of this gender disparity, most research has focused largely on males as there are simply more male subjects than there are female, especially in terms of genetic research. However, a new study just published in Nature magazine has identified a new gene that plays a large role in cases of severe autism in women, as well as some men. This discovery could encourage researchers to study the disorder in families with numerous women with autism.
According to Tychele Turner, an autism researcher at The University of Washington who also co-authored the study, women experience a phenomenon known as the “female protective effect” in which they require significantly more mutations, or more severe ones, than men for them to develop autism. In a climate in which researchers are honing in on specific genetic mutations to better understand the causes of autism, this new study points to the fact that focusing more heavily on women could truly push autism research further as women might be more useful in revealing which mutations cause severe autism.
In the study, Turner and her team looked at the genes of thirteen unrelated women with autism, who also have relatives with autism. This led them to pinpoint a gene called CTNND2, which has significantly more mutations than one would expect to find in a person without autism and thus led them to conclude that CTNND2 likely plays a role in the development of autism.
However, as the pool of subjects was quite small—it is difficult to find conclusive proof with only thirteen participants—the researchers extrapolated their research by combing through the genetic data of thousands of other individuals who had participated in previous autism studies. Says Turner, “We assessed thousands of additional patients to determine if the genetic signal we found was real.” The additional patients showed that, in general, people with autism tend to have mutations in this gene more often than people without. “There are a number of cases — more than we would have expected — that have a severe mutation in this gene,” stated Turner.
However, Turner and her team are quick to point out that discovering that these mutations appear more frequently in people with severe autism does not prove without a doubt that the mutations are the cause behind autism and its symptoms. To further bolster their findings, the researchers also manipulated the genes of zebrafish to cause the mutation and found that the problems it caused issues in a set of molecular changes that have traditionally been linked to autism.
While this study made significant inroads to better understanding the genetic roots of severe autism in women, it has also opened up a whole new horizon of research in which women will be the focus of more studies.