Autism Signs

There is no one genetic variation responsible for autism.  But genetic variations have been found that increase the risk of autism, and, for the first time, researchers have visualized the impact of one such variation (CNTNAP2) on brain function.  According to a press release in Newswise:

Suspecting that [a gene earlier found to be associated with autism] might influence brain activity, the researchers used functional magnetic resonance imaging (fMRI) to scan the brains of 32 children as they performed learning-related tasks. Half of the children had autism, and half did not.
The team's goal was to measure the strength of various communication pathways in different regions of the brain as they connected with each other.
The fMRI images excited the scientists - and confirmed their suspicions.
Regardless of their diagnosis, the children carrying the risk variant showed a disjointed brain. The frontal lobe was over-connected to itself and poorly connected to the rest of the brain. Communication with the back of the brain was particularly diminished.

According to Dr. Daniel Geshwind, a professor of neurology, psychiatry and genetics at UCLA and of the study authors, this project was a first glimpse into how genetic anomalies physically change the way the brain works.  The genes under consideration are known to influence language development, and "...we know where the brain is influenced by the genes.  Variation in the gene is likely to modify activity in those parts of the brain.  We proposed to look at that part of the brain as kids do language-related tasks.  Sure enough we found differences between those with risk and those without."
It's important to note CNTNAP2 can be present with or without symptoms that would qualify for an autism diagnosis.  In fact, says Dr. Geschwind, many children have the variation but are otherwise normal - and thus can adapt to the neural differences.  "Kids with autism," he says, "would have 3-4 additional variants, so they can't adapt to this difference."  What makes this study significant, therefore, is a discovery that could lead to an ability to physically observe the impact of therapy on parts of the brain impacted by genetic differences leading to autism.  Says Geshwind:

With this particular anomaly, long range brain connectivity is diminished in favor of short range brain connectivity.  Can we give a therapy to improve that connectivity?  We can look to see if therapies alter this pattern.   This process is a research tool, not a clinical tool, but we can look at interaction between therapy and brain connectivity.  It gives us a foothold.  We think many genetic variations may be quite modifiable.  Knowing genetic risk allows us to look at the question with a better magnifying glass.

For many parents, of course, the $64,000 question is not "what do autistic symptoms look like," but rather "what causes these symptoms in the first place?" If the problems are a result of spontaneous genetic mutations, what causes those mutations to occur? Says Dr. Geshwind, "No one knows what causes spontaneous mutations, but they happen all the time. That's how evolution occurs. We know of some risk factors; for example evidence is strong that increasing the age of the father increases risk of autism. We don't exactly why this is a risk factor, but it seems likely that as sperm age, they have more chance to accumulate mutations."