Progress toward solving the complex autism puzzle

Related articles

While it s long been clear that there are strong genetic components to autism, it has remained, for the most part, a mystery as to what exactly these genetic components might be. And with new numbers showing that one in every 88 American children will be diagnosed with autism, it has become an even more urgent priority to identify the causes of this condition. Three new studies, all published in the journal Nature, shed some light on the genetic factors that may contribute to autism, and, more importantly, provide suggestions for future autism research.

Teams of scientists led by researchers from Harvard, Yale, and the University of Washington have identified several specific gene mutations that may strongly increase a child s risk of developing autism. To identify these genes, the researchers took a novel approach: They identified rare de novo mutations, which are not passed down from a parent but instead occur spontaneously around the time of conception. To locate these mutations, the researchers obtained genetic material from the blood samples of children with autism as well as their parents and siblings (who had no signs of autism).

In each study, the researchers were able to identify specific genetic mutations that were strongly linked to developing autism. Additionally, their results supported previous findings that have indicated that the risk of having a child with autism increases with the age of the parents. In one of the new studies, the risk is particularly linked to the age of the father; in the University of Washington study, the mutations linked to an autism diagnosis were four times more likely to occur in the father s genetic material than the mother s, and were more common when the father was older, with the risk increasing around age 35.

It had been assumed before that the link to parents age was primarily an issue of mothers getting older, comments ACSH's Dr. Josh Bloom. However, more recently there has been a greater focus on the age of the father, and specifically on the decreasing quality of sperm over time.

Yet while this research may present interesting new ways to look at the relationship between genetic factors and autism, the specific genetic mutations assessed in the studies account only for a tiny fraction of all autism cases. This research is extremely preliminary, and knowing about these specific genes will have essentially no repercussions for the average person, notes Dr. Bloom. The researchers, however, remain optimistic that, now that this line of inquiry into the genetic basis of autism has been identified, they may see the discovery of more new mutations linked to autism in the next few years, which could account for a greater percentage of autism cases.