UCLA’s David Geffen School of Medicine and Semel Institute for Neuroscience and Human Behavior have released a paper that
demonstrate[s] a relationship between frontal lobar connectivity and common genetic variants in CNTNAP2. These data provide a mechanistic link between specific genetic risk for neurodevelopmental disorders and empirical data implicating dysfunction of long-range connections within the frontal lobe in autism. The convergence between genetic findings and cognitive-behavioral models of autism provides evidence that genetic variation at CNTNAP2 predisposes to diseases such as autism in part through modulation of frontal lobe connectivity.
“This is a key piece of the puzzle we’ve been searching for,” said co-principal investigator Dr. Daniel Geschwind, a professor of neurology and psychiatry who holds UCLA’s Gordon and Virginia MacDonald Distinguished Chair in Human Genetics. “Now we can begin to unravel the mystery of how genes rearrange the brain’s circuitry, not only in autism but in many related neurological disorders.”
For anyone genuinely interested in the science behind autism this is fascinating and exciting news. For the very first time science illustrates how a gene variant tied to autism rewires the brain. For those merely interested in continuing to support the idea of an epidemic to uphold their own unscientific but heavily personally invested causation ideas this news will hopefully be a wake up call.
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?
I would respectfully say to Lisa Jo that answering the question of what causes specific genetic mutations was beyond the scope of this particular paper but that without this paper it would’ve been impossible to say with any accuracy how exactly the gene in question affected development. Without that knowledge, looking for answers to causation would be very difficult.
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It’s important to note that the CNTNAP2 genetic variation is carried by 1/3 of the entire general population as noted by the authors of the study:
“The authors emphasized that the patterns of connectivity found in the study still fall along the spectrum of normal gene variation. “One third of the population carries this variant in its DNA,” noted Geschwind. “It’s important to remember that the gene variant alone doesn’t cause autism, it just increases risk.”
Common genetic variants have been implicated in autism, the first was the association between the serotonin transporter genetic variant which is present in over half the general population.
Hakonarnson reported that children with ASDs were more likely than healthy controls to have gene variants on a particular region of chromosome 5. That region is located between two genes, cadherin 9 (CDH9) and cadherin 10 (CDH10), which carry codes to produce neuronal cell-adhesion molecules.
Hakonarnson also claimed that if this mutation could be eliminated 15% of autism cases would disappear. What he did not report in his round of media blitzes is that this common genetic variant is present in 60% of the general population and that every one of the media interviewers he made this claim to have a better than 50/50 chance of possessing this ‘autism’ genetic mutation.
These types of studies always carry the catchy media headlines that appear almost monthly of ‘New Autism Gene Identified!’ The risk carried by common genetic variations is so tiny that the claims by the molecular geneticists always outweigh the evidence