Autism in our DNA? Slew of studies points to genetics as main driver, but there is no ‘autism gene’

Vaccines, chemtrails, GMOs, fluoride, chemicals in food, pollution, chemicals in toys?

The public has been watching the train of fear-driven claims about what causes autism as if it’s ready to run off the rails; each time a vocal advocate of one theorized causal factor or treatment comes forward with an emotionally charged explanation, that runaway train is diverted to a different track, confusing the public even more.

The problem with all of these claims is that this train carries a tremendous amount of momentum—social momentum that causes incredible numbers of parents to question proven healthcare and therapy practices and make foolish choices such as under-vaccinating their children. The other problem is that these claims divert public perception from accurate thinking about the actual science behind autism, or more accurately, autism spectrum disorder.

The causes of autism remain a mystery in much the same way that cancer remains a mystery: there are undoubtedly many influences. What we are learning is that random environmental factors appear to play far less of a role than once thought, and not nearly as much as genes. How much is autism is “in the genes”?

That’s unclear. We do know that there aren’t a few easily identifiable “pure” autism genes. A study just published in Biological Psychiatry used data of 2,576 autism simplex families found in the Simon Simplex Collection to try and see if a homogenous group of autism patients could help them in their search for purer autism genes. They found no such homogenicity when children with similar autism traits and severity were grouped and their genetic data analyzed.

Autism and twins

One way to control for the effect of genes when doing research is to look at genetically homogeneous groups. One of the best ways of understanding what effect genes do—and don’t—play in certain diseases and disorders is to look at human twins.

twins_4Recent research in the Journal of the American Medical Association Psychiatry found that the genetic heritability of autism spectrum disorder is high compared with other factors. In fact, the researchers found that 56 percent – 95 percent of the effect is estimated to be genetic, according to a study of 258 twins suggests. (Genetic influences on autism are estimated to be between 74-98 percent according to research by the Medical Research Council in the UK.)

The use of monozygotic twins and dizygotic twins in this study (the difference described here) allowed the researchers to study pairs of twins raised by their parents in the same household, which allowed researchers to look at prevalence rates of autism while also having pairs of twins exposed largely to the same environmental factors.

If one identical twin has autism spectrum disorder, the other twin has a 76 percent chance of also being diagnosed with it, according to the study. The numbers were lower for fraternal twins. The percentage of fraternal twins who each share an ASD diagnosis is 34 percent for same-sex twins and 18 percent for boy-girl pairs

We know that genes is the primary driver of autism. We don’t know which genes, however. “There may be perhaps hundreds of genes that contribute to autistic traits,” said Francesca Happé of King’s College London.

It’s important to note that the authors of this twin study found a significant effect of environment, but the effect of environment was about one-half to one-third as the genetic effect. “Some parents are concerned whether things like high pollution might be causing autism,” Happé noted.

“We are still a long way from knowing what leads to autism,” added Dr. Judith Brown, of the UK’s National Autistic Society. “Autism is a highly complex story of genes not only interacting with other genes, but with non-genetic factors too.

This large population-based twin sample is significant because it helps us to understand much more about the role genetics play in autism and opens up the possibility of whole families gaining a better understanding of a condition they may share.

However, we are still a long way from knowing what leads to autism. What people with condition, their families and carers need most of all is access now to the right kind of support to be able to lead full lives.

Prodigies share genetic mutation with people with autism

The genetic underpinnings of autism were further underscored by a just released study that found that child prodigies share some of the same genetic variations with people who have autism. The Human Heredity study involved five child prodigies and their families—not a large sampling. These shared genetic markers occur on chromosome 1, according to Joanne Ruthsatz, co-author of the study and assistant professor of psychology at Ohio State’s Mansfield campus, who worked with a team from Ohio State University and Nationwide Children’s Hospital in Columbus.

The researchers have not identified the actual mutations. “We now know what connects prodigy with autism. What we want to know is what distinguishes them,” said Ruthsatz. “We have a strong suspicion that there’s a genetic component to that, as well, and that’s the focus of our future work.

Paternal link

Another small study, published online in the International Journal of Epidemiology earlier in April in the journal International Journal of Epidemiology, found a possible association between the disorder and a father’s epigenetic tags, which help regulate genes’ activity. Doctors can detect epigenetic changes by testing sperm.660_sperm_to_ovule

Researchers identified more than 190 sites where the presence or absence of a tag was statistically related to whether the father’s child would show early signs of autism. “If epigenetic changes are being passed from fathers to their children, we should be able to detect them in sperm,” said Professor Daniele Fallin, said co-lead investigator, professor and chair of the Department of Mental Health in the Bloomberg School of Public Health.

There has also been novel research looking at blood-based biomarkers to identify autism spectrum disorder. One of the holy grails of medicine is to find quantitative biomarkers for any given disease state; There’s a great deal of satisfaction in being able to discuss a numerical threshold where the presence of a disease ‘is’ or ‘isn’t.’ The science isn’t complete, and this current research has only been performed in male infants and toddlers, and it’s currently estimated to be accurate about three-quarters of the time.

Much more will be coming soon on these themes, because for example the ‘environmental’ effect described above is only as specific as general region of where the twins were located, and didn’t probe into or elucidate anything further to that end. Rough estimates are that over a hundred to two hundred or more genes are involved or implicated in autism spectrum disorder. Vastly this is related to genetic heritability within families, but also whether these genes express in certain ways or not becomes the much more complicated factor associated with life experiences and so-called environmental exposures. Additionally, because autism spectrum disorder describes a range of conditions and behaviors rather than a single disease, and manifests in very different ways and levels of severity, pinning down a single determinant has been considered by experts to be all but ruled-out.

Ben Locwin, Ph.D., MBA, MS is a contributor to the Genetic Literacy Project and is an author of a wide variety of scientific articles for books and magazines. He is also a researcher and consultant for a variety of industries including behavioral and psychological, aerospace, food and nutrition, pharmaceutical, and academic. Follow him at @BenLocwin.

Jon Entine, executive director of the Genetic Literacy Project, is a senior fellow at the World Food Center Institute for Food and Agricultural Literacy, University of California-Davis. Follow @JonEntine on Twitter

48 thoughts on “Autism in our DNA? Slew of studies points to genetics as main driver, but there is no ‘autism gene’”

  1. Looking at the two hemispheres of the brain, with the right being the emotional and the left the cognitive. It appears to me that the person with Autism might have a problem with the right. Think for instance of the areaT4-T6 where identifying facial expressions take place. What I am wondering is, what specifically happens during brain development? From the 3rd. week to the 3rd. trimester brain cells are being developed and brain pathways are being formed from the 3rd. trimester until the age of 2. How possible would it be to identify the problem during the latter period?

    • Interesting questions. Sperry’s (1981) work which led to formulating the ‘left-brain, right-brain’ hypothesis has been shown to be incorrect. However, your point about T4 for example, or the fusiform face area in particular is a very important one. Social interactions, which can become difficult or impossible in those with autism must involve the linkage between the fusiform gyrus, the amygdala, and other structures. Certainly, as you rightly have pointed out, the neuronal connections are being developed through early childhood, but a great deal of neuronal pruning is occurring around that time – greatly reducing the number of connections, presumably to reinforce those which become more important. In fact, synaptic pruning has been recently implicated, or at least potentially associated (see second link below).

    • you forget that autism is a spectrum these days.. and in this spectrum you got Aspergers syndrome. people with Aspergers can show strong autistic traits, but are quite high functioning. they do not have any issue with identifying facial expressions

        • no they dont. i have aspergers myself, and know many other people that are diagnosed aswell, and noone of them have issues identifying facial expressions. we might have a hard time reading a social situation, and body language.. but thats not the same as being completely “blind” when it comes the emotinal and cognitive recognition of human facial expressions.

          • generalizations based on your own symptoms exclude the majority of data, i also have been given the lable of an aspie and i can’t make eye contact for extended time or at all. i found some very helpful Ted talks that actually adress how the reclassifications were simply fixing an error by the early doctors

          • Its not a “generalization”. The majority of the data clearly shows that most aspies do NOT have a issue with identifying facial expressions. I have a suspicous that you dont actually understand this subject, nor understand what we are actually talking about. What do you think “identifying facial expressions” means? That sentence has absolutely nothing to do with “eye contact”.
            People with traditional autism, have cognitive issues, aswell as severe language/speech delay.
            One of their issues is the inhability to identify facial expressions. They cannot differentiate between a face that is smiling/happy, or a face that is sad or angry.
            If you list up a bunch of pictures of People making normal and even highly exagerrated facial expressions infront of a person with traditional autism, and then tell him to “point at at a happy/smiling face”, he will most likely point at a completely different face. Sometimes mistaking a “happy face” for an angry or even a sad face.

            They are completely “blind” when it comes to identification of facial expressions and emotions in others.

            These issues are NOT existent in Aspergers Syndrome. Hence why it is listed as “high functioning” on the spectrum

          • you are funny, did you even bother to pay attention to the video i posted, or are you one of these smartasses that thinks he knows more than the experts?? what am i thinking, of corse you are in the later category, you are an aspie.. (see how that works?)
            pay attention to the contents of the video link i posted then stop making an idiot of yourself.. my children are actually on the high functioning side of things, where Aspergers is located. and they do, have the problem, of facial identification and emotional reading. we have spent years training them above and beyond the regular growth patterns to be able to get them to recognize the various expressions and the emotional attachments and the proper wording to express their own various feelings and triggers.. and quite frankly, sir, i will take the words of people like their doctors and mentors, and the other experts who actually got invited to a ted talk.. over random people on the internet with no verrification studies or anything but their own words to back them up..

          • So thats how you are going to do this, ey? Going down on a child level and call people idiots for opposing you. Anyone can be invited to a TED. Just because someone made a speech does not make it a fact. Most TEDs these days are nothing but an outlet for opinions, not “proffesionality”. Also, claiming that your children is “High functioning” does not make it a more valid claim.. You didnt even specificy that they had aspergers, you only stated that they were “up there” WITH aspergers. Do they have aspergers or do they not?? Because we are talking specifically about aspergers, anything else is irrelevant! Also, first you used yourself as an example, but now youre changing the subject towards your children which you dont even specify to have Aspergers.

            There are little studies to link in the first place, because its NOT fully understood. In fact, face recognition issues is actually more common than autism itself.


            And with the “autism spectrum” that the americans created, few studies actually focuses on subtypes in the spectrum like Aspergers. Meaning that there can be large amounts of flawed and biased statistics and interpritations of those stats.
            This is not something i just simply use my “own words” to back up my claim. This is based of every autistic person i know, in my family and myself. Easily going past 20 people with diagnosed aspergers, and NONE of them have facial recognition issues on the level of the lower functioning type.
            When you have so completely opposite results, then there is something wrong with the current diagnostic definition and research

          • so, i take it you didn’t pay attention to the ted talk either??? well lemie spell it out for you.. the shifting in the diagnoses requirements came about as people realized that the various diagnoses in these various books and such were describing virtually identical scenarios with only a handful of variants. there was even a “scientific american frontiers ” that tackled the issue witch you actually get the presenter, spelling it out quite clearly “but that sounds like…” .. and as pointed out by the person who is in the ted talk, the occurrences of symptoms for autism were much more common than the original identifying doctor wanted to deal with so he restricted his personal diagnoses criteria to include the most severe cases.. meantime, Asperger was noticing the more generalized nature of these symptoms and the prevailances of the more functional peoples, who were using more formalized languages, and avoiding eye contact and showed limited fields if interest as well.. the two are the same..

          • Cloud, Spectrum, Syndrome, Venn diagram. It’s fuzzy, you might all have 30 diagnostic traits but they don’t have to be the same thirty to get you diagnosed. OF COURSE, if you are each extrapolating from your extended families, your going to highlight those traits you DON’T have in common.

          • so, i pointed out an old show, “scientific american fronteers” from before the reclassification.. where the presenter goes through the process of looking at these differently classified conditions, and explores the similatrities that led to the outcome of the shift… also, as i stated in a previous comment, the person, who did the initial classification, deliberately narrowed the diagnoses cryteria for the most extreme cases. in my case, i was not in a family with a history of diagnoses at any extended or non extended level. so, again with the presumptiveness that we deal with constantly, and, from what it sounds like, and the way you emphasized your words, you have actual family issues

          • and, my nephews, my nieces,have subsequently been given diagnoses of being on the spectrum, independantly of my own

          • Hiya, sorry I couldn’t follow your first reply at all, probably my bad: my comment is to Gero and Swann as well as yourself. I’ll try again.

            Your unlikely to share the same diagnostic traits with complete strangers. You are likely to share them with your family. Any diagnostic you don’t share with complete strangers will lead to this kind of argument. You are probably ALL right in what you are saying about faces. It is just not a diagnostic you share with complete strangers. Your probably arguing about a 5% of Aspie you don’t have in common. Follow me now?

          • sharing the same diagnostic traights,with complete strangers is how we grasp the fact that there is a “condition” or a disease that exists. the recent Zika virus, and the tie to microcephaly is a good example of how that works. microcephaly, is normally one of those genetic anomalies and suddenly there was an surge in cases that was later tied to the virus and it’s transmitting through mosquito bites
            Generalized statements don’t work, that was my point about his point. and it doesn’t change the truth about the condition and it’s history, Asperger saw the more generalized patterns while the originator of the term, “autisim” was extremely specific and actually turned away families just because he could as pointed out by the people in the ted talk and backed up by examining the actual conditions

          • I’m not understanding you and I’m pretty certain you’re not understanding me. Thanks for putting Silbereman’s talk up, I knew the individual bits of the jigsaw but I hadn’t consciously thought of it the way he explained it. I was hearing ‘Connor’; not Kanner; though, it took me a while to work out what he was talking about! :smiles:

            I agree with you, Aspies can have trouble with facial expressions. I’ve seen that in Aspie autobiography and in the work of several psychologists in the field; Tony Attwood springs to mind.

          • you were reminding people that they are most likely to comapre their own condition to those of their relatives and not those of total strangers.. and i was pointing out, that’s not the way you determine a malady in the first place. multiple peoples with similar manifestations.. equal identification of a malady be it asperger’s or anything else.. and, please stop making me have to shrink the words involved.. “dumming things down” hurts my head that is also, a high functioning autism thing..

          • Ah! right, you aren’t understanding me. I’ll try again tomorrow. What do you mean by “shrink the words involved” and “dumbing things down”? I’m English and your usage of the language is rather odd to me.

          • i think i understood quite clearly, if that wasn’t your point than why was that your wording? as far as the expressions i used, they are referring to the tendancy to use the more detailed and complex wordings as compared to people that just say thing in the simplest vernacular “dumbing something down” an example is actually in the choice of “vernacular” instead of “local speech patterns” go back through my comments and try again.. i appreciate the fact that you verify the asertion about emotional expression, however the conversation had progressed beyond said topic into the history of the maladiees being discussed and a continued repitition of statements about said history whitch you seem to have completely missed while continuing in the previous mindset

          • I’ll bow out, you’ve lost me completely and I can’t understand anything you are saying. My apologies.

          • then reread. and allow yourself time to think.. by all means.. i will not repeat myself again

          • Sorry Merlith, I believe you, that you do not have this problem, but I do. I have Aspergers and I do have even at 56 have significant problems reading expressions and intents in others. It was most impossible when I was young and one of the worst things was I got a lot of beatings because I failed to see rising anger in adults and others and could not learn avoidance so developed a very anxious condition. I do however now consider myself better at reading emotions (I already understand them just as anyone else does) but only in people I have come to know overtime, and then I can download, as it were a visual memory blue-print to the emotion expressed by them in my inner databank and social interaction flows without the anxiety. I cannot read people I have just met but if I am with people I know, I can learn and observe from the new interaction the expression style of the new ones and assimilate much quicker. Please understand Merlith we are all different. Your experience is not universally everyone’s experience, when you have met one aspie, you have only met one aspie.

      • asperger, did his research at the same time Autism was being acknowleged, and showed that it was waaaay more prevalent than the limited diagnoses of the person who gave the disorder it’s lable. that guy, regularly turned away patients for not showing symptoms that were severe enough..

      • Most people with Aspergers do in fact have difficulty with identifying facial expressions – the more subtle and complex emotions, not the obvious common ones. Many of them also have difficulty with identifying people’s faces even if they know them (prosopagnosia).

    • Brilliant! My hypothesis is that an over-active stress response in early pregnancy impedes a neurodevoelopmental critical step, which, if missed due to high levels of neurotoxic cortisol, does not occur and leaves a neuropsychological deficit. But, then, to me, it’s all about stress anyway, and stress is the causitive factor for a real understanding of ALL human disease. To be more precise: population density stress. All top ten killers of modern, urban humans have a stress etiology and are caused by high cortisol levels. Extensive documentation (over 100 refs) can be found in my free online e-book, “Stress R Us”. Just Google the title.

      • doesn’t demonstrate how could autism have raised from 0,2% in 1999 to now almost 2%. unless you suggest depression or stress has risen tens if not hundreds of times since 1999. nope. stress has been a natural thing throughout the existence of mankind but autism is a modern disease, which means it’s caused by a modern phenomenom, and although stress is more prevalent these days it’s hardly a new or such a big factor resulting in 10x increase in autism within the past 18 years.

        • Thanks for the stats: 0.2-2,0% of an expanding population on increasingly stressed, crowded, overpopulated humans is a 1000% increase in just 18 years and pretty much proves my point. Thanks for that. The same rapid rises in all the other “diseases of civilization” are also occurring. The critical biomarker to watch is the rapid decrease in fertility. Nature is making an adjustment and we aren’t in Her plan for the future.

  2. Interesting article, thanks. The RNA blood test for toddlers looks really promising. Someday soon, we might have a test like for PKU.

    Anyway, couple studies published after this article. The “over a hundred to two hundred or more genes are involved” has been refined somewhat.

    New Autism Genes Are Revealed in Largest-Ever Study

    In the largest, most comprehensive genomic analysis of autism spectrum disorder (ASD) conducted to date, an international research team led by UC San Francisco scientists has identified 65 genes that play a role in the disorder, 28 of which are reported with “very high confidence,” meaning that there is 99 percent certainty that these genes contribute to the risk of developing ASD.

    In addition, the study confirms six “risk regions”—segments of chromosomes that contain several genes, which, when lost or gained, contribute to ASD risk. In combination with the 65 risk genes, this results in 71 ASD risk loci, or locations.

  3. I want to tattoo the second paragraph onto my body. What a concise answer to Autism (in my case). Every individual in my husbands family has Autism, mostly high functioning, 5 generations of 14 people. Whatever AS they have it’s defiantly genetic. If this was not proof enough, it would be, after i came to the terms with the statistical chances that I marry into an Autistic family after having being raised by an Autistic family of 5. (I was adopted.) So my biological unrelated side is also 5 generations of over 20 people that have it. It’s unquestionable amazing,(horrible for me) but amazing never the less.

  4. You write with confidence about autism,and you sound like a fool.In the toxic environment we exist in,any of those insults you mention may be triggering this calamity.Proven healthcare and therapies practises?you kidding me? the $ will return more value if it was invested in research.

    • poisons in the vaccines? shot down, toxins in the environment post natal? shot down. ineutero toxins? mostly debunked.
      thing is… and this is the part that lots of people miss when making blanket assumptions like the ones you are making, there was a redefinition of autism to fit the evidences available. AFTER the removal of the thymerosol. valid ties to chemicals ineutero are leaning toward the antidepressants , the specialized seritonin reuptake inhibitors, witch were already tied to other birth defects
      as far as toxins in the outer environment, they lead to overload, they lead to the break down of a “normal” behavior pattern by sending the autistic person into sensory overload. the only thing you can do… is teach the coping skills for those that are able to grasp them.
      research into the causes and the therapies has identified the genetic signatures but it doesn’t bring the children to functionality

  5. “The causes of autism remain a mystery in much the same way that cancer remains a mystery”
    Let’s not forget, “cancer” is not one but many diseases and some are not as “mysterious” as they once were – some have very distinctive biologic features, clinical courses, and therapies. Some have identifiable genetic causes – t(15;17) in acute promyelocytic leukemia/APL and t(9;22) in CML – and very effective “targeted” therapies, ATRA for APL and Gleevec for CML (and there are other examples of known causes and targeted therapies).

  6. “The other problem is that these claims divert public perception from
    accurate thinking about the actual science behind autism, or more
    accurately, autism spectrum disorder.”

    This pinpoints the incredible density of most discussion and research on autism.

    Imagine if colds, flu, pneumonia, tuberculosis and a myriad of other diseases were combined in, say, a flu spectrum disorder in discussion and research.

    Asperger’s syndrome is the most common disease [or more properly syndrome] to be linked to autism, though the two have little in common beyond some loosely defined symptoms. The extended language development disorder of autistics is rarely encountered in “arpies.”

    What do we know about it? A lifetime of struggle with autism is all.

    Best, Terry

  7. I have a question. I have Autism Spectrum Disorder and the kind I have is High Functioning Autism. My eldest daughter Candace also has Autism. So is it possible that I may have genetically pass it on to my daughter and would it mean that I have Autism in my genetics because my mother who is now deceased said that if I have a kid I am highly likely to have a child with Autism. I was needing to know if I passed Autism on genetically?

  8. we cannot isolate genes from things which affect our genes. but let’s entertain the thought, that it’s our genes which are going haywire cos autism has increases 100% since 1999, then there definitely is something that’s driving the gene mutations, cos change is happening, and rapidly. i’d say it’s the environment, the 3 pillars of death, meaning the pharmaceutical companies, pollution and radiation which are to blame all the way and genes are just in the long line of being their victims.

  9. The IRONY! You say parents are dumb to boycott vaccines but LITTLE do you know that mercury is in the vaccines and although it’s a small amount per vaccine, it adds up especially when children these days are given 69 DOSES! Guess what mercury does? It inhibits the CPOX enzyme and when the CPOX enzyme is inhibited coproporphyrins build up in the body. Surprisingly enough children with autism were found to have elevated amounts of coproporphyrins in their urine. Do NOT put all of your trust in the healthcare system! They are human, like you and me.

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