Do You Need an Advanced Degree to Understand The Genetics of Autism?
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Nestor L. Lopez-Duran Ph.D. runs a blog called Translating Autism. Here's how he describes his project:
I'm the founder of the Translating Research Project, a series of informational blogs designed to rapidly disseminate scientific research findings in neurological and psychiatric childhood disorders and translate these findings into information useful to parents, educators, and clinicians.From time to time I tap into Translating Autism to get a more thorough understanding of the thinking behind a particular autism study, or to find out more about the history of a particular theory.
Today, Translating Autism takes a "Cliff Note" look at an article which "reviews the literature" on autism and genetics. Bear in mind that Lopez-Duran is simplifying the information in the article so that ordinary folks can easily make sense of what we've learned about the relationship of autism to genetics.
Here's just a snippet from his simplified information:
RELN: Reelin is a protein that is associated with neural migration during brain development. At least five studies have found an association between variants of the RELN gene and autism (Ashley-Koch et al., 2007; Perisco et al., 2002, 2001; Zhang et al., 2002; Dutta et al., 2007). Furthermore, mutant mice that do not have a section of the RELN gene have the same atypical cortical organization that is found in post-mortem studies of autism.I am hoping fervently that, as a non-scientist, I am not alone in feeling baffled by this information.PTEN: The PTEN is a tumor suppressor gene associated with the prevention of uncontrolled cell growth. Mutations in the PTEN gene is associated with macrocephaly. Four studies have documented an association between the PTEN gene and autism among children with macrocephaly (Butler et al., 2005; Buxbaum et al., 2007; Boccone et al., 2006; Herman et al., 2007).
To begin with, of course, I know an association is not a causal connection. For example, beer drinking may be associated with spectator sports - but the beer doesn't cause the sports, and the sports don't cause the beer. So when we're told that a gene is "associated" with some marker for autism, we shouldn't leap to the conclusion that there's any kind of causal connection between, say, PTEN, macrocephaly (oversized brain) and autism.
Yet we do know that there's a connection between autism and unusually fast head growth during the first few years of life.
So... What does this finding mean? Can we use this information?
Those of us who are searching for meaning in autism research may be tempted to leap to conclusions. "Ah hah! There IS a genetic connection between autism and head size. That must mean that autism is a genetic disorder!" But of course the Cliff Notes version of the study says nothing like that. In fact, it really says nothing definitive at all. It simply points to an association.
And since I, at least, am not a neuroscientist, I really don't know what PTEN or RLEN are. Yes, they're genes whose purpose is understood - but how do they operate? What else, if anything, do they control? How do they interact with other genes? Understanding all of these things and many more are critical in making sense of genetic research - but even the "cliff notes" version leaves me feeling unsure of my ground.
Like most parents of children with autism, I've been reading, researching and checking my autism facts for years. But none of that work has prepared me to analyze genetic studies and intelligently comment on their validity or significance. The truth is, genetics is an extremely technical field - and very few of us are really ready to read genetic studies and reliably assign significance to findings.
Do you really need an advanced degree to understand the genetics of autism? In the most basic sense, of course, the answer is "no" - anyone can grasp the fact that identical twins are far more likely to share autism than are fraternal twins. And no advanced study is required to make sense of the discovery that spontaneous (not inherited) genetic mutations seem to be associated with many cases of autism.
But once you start wading deeper into the subtleties of genetics, the concepts become highly technical - and real knowledge of biochemistry actually matters. It's tempting to think that these studies can be easily simplified. But where researchers can competently swim, most of us are in way over our heads.
Comments
When we cite the rate of autism in twins, we always fail to note that these children have been exposed to identical environmental conditions/insults, likely been given their vaccines from the same vial, etc. –i.e., if they’re both on the spectrum, it’s too easy to jump to the conclusion that it must have been caused by genes rather than by toxic exposure.
Since there is a epidemic of autism, there has to be an environmental trigger: genetics cannot cause an epidemic.
A major environmental trigger has already been identified. Michael Waldman’s research (2006)[1] has proven that autism is strongly correlated with early childhood exposure to television. Such exposure, like autism, has risen dramatically in recent years. These results do not prove that TV causes autism, but that early exposure to TV seriously increases the risk of autism.
In scientific terms, Waldman’s research is highly convincing. Nevertheless is has been ignored or dismissed. Our culture is so enamored of television and the computer that it resists the accumulating evidence that early over-exposure leads to behavioral problems in children. Parents of autistic children dread feeling blamed and so resist the possibility that their use of television, DVDs, or computer games may inadvertently have triggered autism.
Both the public and many researchers have been misled by the evidence that autism is correlated with genetic factors. In fact the genetic evidence shows that genetic factors may predispose an infant to autism, but that genetic factors alone do not cause autism. For example, when one genetically identical twin is autistic, the other may not be autistic.
Research on autism is often flawed by mechanistic assumptions about the brain. It is now well-established that biological structures are not mechanisms but dynamic systems. Unlike mechanisms, dynamic systems organize themselves with extensive input from the environment. These issues, and their implications for autism, are explained more fully in my on-line article in Dynamical Psychology (2004)[2].
Meanwhile, Waldman’s results cannot be dismissed. Their scientific and statistical validity is clear.
(My own scientific experience was as a molecular biologist at Duke University, M.I.T., and the M.R.C. Laboratories in Cambridge, England.)
Maxson J. McDowell PhD, LMSW, LP
(1) www.johnson.cornell.edu/faculty/profiles/wald…
(2) www.jungny.com/Autism-Statistical.html
Do You Need an Advanced Degree to Understand The Genetics of Autism
“An association is not a causal connection.” Good point. But it seems that a subtext to a lot of the autism-spectrum awareness writing is akin to the tobacco industry’s attitude toward smoking and cancer: “An association is not a causal connection.”
Are only associations with environmental factors such as with vaccines to be enthusiastically accepted by the autism community?
The ‘’The Genetics of Autism'’ in the headline of the article seem to be defined as unproven by any genetic research by the tone of the body of the article.
Someone proposed a study of unvaccinated children to investigate the incidence of autism in that population… If the genetic research currently being conducted is all a dead end, which is it being continued at such an explosive level?
J Lorre - you wrote “The ‘’The Genetics of Autism’’ in the headline of the article seem to be defined as unproven by any genetic research by the tone of the body of the article. Someone proposed a study of unvaccinated children to investigate the incidence of autism in that population… If the genetic research currently being conducted is all a dead end, which is it being continued at such an explosive level?”
Not sure I completely understand your point, but MY point was not to say that the genetic research was useless. Rather I wanted to make the point that it is complex, technical, and tough to understand if you’re not versed in biochemistry!
I’m guessing that the “explosive level” you’re referring to is the fast pace at which autism diagnoses are growing. Of course, there’s a lot of controversy over whether or not autism is “really” growing at all, since so many of those people diagnosed with autism spectrum disorders would not have received an autism diagnosis prior to 1990 (when diagnostic criteria were radically changed).
All that set aside, though, I personally would applaud research looking at unvaccinated versus vaccinated populations. The only problem is - who is doing the research? Generation Rescue did a sort of mock research study (trying to prove to the CDC that it could be done) - but of course GenRescue has its own agenda. Many feel the CDC has ITS own agenda too.
Whom would you trust to do a proper, unbiased research study on this topic?
Best,
Lisa (autism guide)
Since there is a epidemic of autism, there has to be an environmental trigger: genetics cannot cause an epidemic.
What evidence do you have for an autism epidemic? Are you talking about the entire spectrum, or just Kanner’s autism?
Lisa — THANK YOU for getting this right.
There is a complex interplay between genes and environment. Not so complex that it is beyond human ability to eventually understand; but certainly complex enough to elude our CURRENT understanding.
It may turn out that environmental exposures cause the genetic mutations, which, in turn, lead to susceptibility to ASD.
It may be intergenerational, by way of epigenetic changes, which can lead to transcription errors, spontaneous gene mutations, etc.
It may be any number of things. It’s not wrong to speculate and think about the interplay.
But it is kind of silly to claim certainty about (1) t.v. causing autism [why do Amish kids get autism?], or (2) there is no autism epidemic / kanners is the only real autism, the rest is pretend autism which has just changed labels from something else.
Anne-VR makes her point AWESOMELY! Twin studies are classically cited as the definitive gene-enviro litmus test. (…twins reared together / twins reared apart, etc.) But that ignores that twins share the same environment in utero.
Implicit in Anne-VR’s point, however, is the ONE THING WE CAN CONCLUDE WITH ABSOLUTE CERTAINTY about GENES and AUTISM - namely, that GENES ARE NOT THE SOLE CAUSE OF AUTISM.
If they were, then environment wouldn’t matter and the twin concordance would be 100%.
Genes probably play a part of the causal role, unlike beer and spectator sports. But Lisa is absolutely right that we have to stop short until we know more. All we KNOW at this point is that there is an association.
Immunizations cannot be ruled out as an environmental trigger. Again, the effect may be intergenerational / cumulative / or synergistic. Immunizations affect the immune system (duh). Immunizations certainly qualify as environmental are toxic exposures. Environmental exposures affect the epigenome. So that’s not a far-fetched connection to consider.
I find the RELN discussion especially interesting. We’re off into speculation here, but it just “rings true”, because the neural migration (formation of axonal connections and establishing basic neural pathways - white matter linking gray matter, and structures within gray matter) makes PERFECT sense.
Observing my son regress at 18 months, I had a sense that astrocytes were busy ripping out previously established “good” links. My son went from talking to not talking, motor skills declined, global intellect plummeted, etc. etc. It was as if his hard drive was being reformatted.
Now, at age 31 mos, he is talking again (praise be to God). But his speech is coming from a different “place” than before. His acquisition is slow and quirky, but he has a legitimate grasp of word meanings. He’s still not stringing words together like he was at 12 months. I get the sense that his brain is finding new pathways to replace the old ones that were cut off. Thankfully, children’s brains are very plastic, which seems to allow for compensation to take place. ABA no doubt exercises and develops the new pathways.
Every little drop of information goes into the bucket. The bucket will eventually be full and we will know what causes autism and hopefully that will be followed soon thereafter by a cure or treatment.
Still need to do unbiased (?) studies on immunizations & asd.
Twin studies almost always compare fraternal twins (shared same environment & half of genes) with identical twins (shere same environment and all genes). This is how they can differentiate genetic from environmental influence.