Washington University School of Medicine in St. Louis released a study in the American Journal of Psychiatry regarding speech delay patterns of siblings of children with Autism, as reported by Physorg.com. The report shows a higher number of siblings of children with autism have speech delay when compared to siblings of neurotypical children.
The implications are that children who have a sibling with autism are more likely to show speech delay, whether that sibling is older or younger than the child with autism. Therefore, the speech delay can show a propensity for autism, though not severe enough for the direct diagnosis. It also shows that some girls with similar traits may even be considered "autistic," even though the diagnosis was not given to them, therefore showing a possible narrowing in the gender differences in autism diagnosis.
So why is it important? The current scientific theory that has actually been proven through clinical studies (as apposed to many other claims) is that autism is genetic, resulting from a number of genes, any one of them can cause autistic symptoms to show at some level. The higher the concentration of "autism genes," the more pronounced the behavior. Siblings may have inherited some genes, but not enough to cause the behavior needed to be diagnosed "autistic".
It also explains the prevalence of Autism within certain families and along specific genetic lines. Unlike other yet to be proven theories that suggest environmental stimuli as the cause, genetic traits that are passed on stand out in the research done in this article.
So that's great to know, but what does it mean for me as a parent of an autistic child? It means I need to be alert for any signs of Autism in my other child, in order to catch it early, but also take hope in knowing that anything I see, such as delayed speech, could just be a small marker that is quickly overcome. It's very possible that any sign of autism in my other child could be so mild as to not be diagnosed as Autism. And, of course, it takes less of the mystery away from Autism, making it less of a scary diagnosis. The more understanding we have, the better we as parents can cope. At least, that is what I feel.