As with many complex disorders, causation is generally thought to involve some forms of genetic risk interacting with some forms of non-genetic environmental exposure. The balance of genetic risk and environmental exposure likely varies across the spectrum of ASD. .......... Researchers are working to better understand the interaction of genetic vulnerability with developmental experiences, such as a specific environmental exposure. While gene-environment interactions have been hypothesized to play a role in many medical disorders, these interactions have been difficult to prove or disprove beyond statistical tests showing that some genetic subgroups have a greater response to some environmental factor. ............ Progress in identifying environmental factors which increase autism risk has been made recently (Eskenazi et al., 2007; Palmer et al., 2006; Palmer, Blanchard, & Wood, 2009; Rauh et al., 2006; Roberts et al., 2007; Windham et al., 2006), although this area of research has received less scientific attention and far fewer research dollars than genetic risk factors. Environmental factors may be pertinent not only to brain development but also to chronic systemic features of at least some subgroups of ASD.
- The 2010 Interagency Autism Coordinating Committee Strategic Plan for Autism Spectrum Disorder Research - January 19, 2010, Question 3: What Caused This To Happen and Can It Be Prevented?
The 2010 IACC Strategic Plan statement that environmentally focused autism research has been under funded and largely ignored could properly be characterized as a long overdue confession by the autism research establishment. Autism research has been focused overwhelmingly on genetic causes of autism to the near exclusion of environmentally focused research. for well over a decade with potentially serious consequences for our current understanding of possible autism causes and treatments. Given that imbalance it is perfectly understandable that few potential environmental causes of autism have been identified or confirmed through research. If we don't open our eyes and look, if we don't do the research, then we will not find environmental causes of autism.
The overwhelming imbalance in favor of genetically based autism research was identified over a decade ago by researcher Teresa Binstock in her 1999 description of the "It's gotta be genetic" autism research paradigm. Binstock pointed to the culprit - the old guard network that insisted that autism research be genetically focused in order to have any hope of receiving public funded research dollars:
My own hunch is that the NIH and NIMH will not change from within; the senior practitioners of the "it's gotta be genetic" model have too much influence. Just as Semmelweiss and his data were suppressed, so too will the NIH/NIMH autism-research insiders continue to act against the the growing body of new data in autism; the NIH's pro-genetic old-timers will cling to their paradigm and its funding. As a result, change within the NIH and NIMH will have to be initiated from outside those tax-supported corporations.
The imbalance in favor of genetic over environmental focused autism research has resulted in a call for more balance from many sources and hopefully that call will result in more than lip service. There have been signs of an autism research paradigm shift over the past few years from the purely genetic model of autism to one which looks at autism as the result of a genetic and environmental interaction but the pace of change has been far slower than first hoped as pointed out by the 2010 IACC Strategic Plan above , by Dr. Irva Hertz-Picciotto and by Dr. Jon Poling.
Too much time has been wasted on the irrational insistence that autism research must be genetically focused. We have lost the knowledge that years of more balanced autism research, with greater attention to potential environmental factors, might have given us. We must find that balance as we move forward or more knowledge, and possibly treatments and cures, will continue to be lost.
Environmentally focused autism research must receive more attention and funding. Even the IACC has recognized the imbalance in favor of genetic over environmentally focused research.
It is now time to redress the imbalance.
autism
The IACC has recognized this imbalance, now hopefully they will act on it. There is so much evidence that autism is not purely genetic. Identical twin studies that have been done do not show 100% incidence of autism, which completely blows the pure genetic theory out of the water. And then there are families like mine, with no family history of autism, and now with a child with a regression into autism.
ReplyDeleteAndrea, identical twins are not identical copies of each other. Less than 2% of such twins have different eye colors. The genetics of autism is much more complex.
ReplyDeleteEnvironmental factors have not been ruled out, but I have not read where researchers believe that MZ twin concordance is too low to support a purely genetic origin.
Ian MacGregor your understanding of what researchers have determined with respect to twins and non genetic causes appears to be at odds with the understanding of Psychologist Simon Baron-Cohen who I have previously quoted on this blog site at:
ReplyDeletehttp://autisminnb.blogspot.com/2009/01/simon-baron-cohen-reiterates-autism.html
"Psychologist Simon Baron-Cohen of the Cambridge University Autism Research Centre has reiterated his previously stated position that autism results from the interaction of genetic AND environmental factors. In an exchange with a parent published on the One Click Group site Professor Baron-Cohen stated:
The One-Click Group seems to be a website for those who want to see more research into environmental risk factors in autism, and to me this seems to be a very worthy agenda. We know that autism is not 100% genetic in origin, since in the case of identical twins (who share 100% of their genes), there are instances of one twin having autism and the other not having it. In fact, the likelihood of the co-twin also having autism where one of them has it (in monozygotic (MZ) pairs) is about 60%. This means that there must be some non-genetic (i.e., environmental) factors that are part of the cause of autism. ...... I hope the above statement shows clearly and unambiguously that I regard autism as most likely the result of a gene-environment interaction.
Professor Baron-Cohen made the same point in a December 2007 interview piece published on TimesOnLine, Freedom of Expression:
Studies of twins have established that it is not 100 per cent genetic, since even among identical twins, when one has autism, the likelihood of both twins having autism is only about 60 per cent. This means there must also be an environmental component, but what it is remains unknown."
If even eye color which I think is controlled by either 5 or 6 genes is not 100% shared by MZ twins, then would expect autism to be? There are two figures thrown out for concordance. The 60% figure is for autisitc disorder, the concordance for ASD is at least 90%.
ReplyDeleteTwins usually grow up in the same environment so why would we see any difference based on environmental triggers? Why is the rate of concordance in fraternal twins the same as it is for siblings who are not part of multiple births?
I hope there is an environmental trigger, an it found soon. I fear though there is not
Ian, like Harold said they share 100% of their genes. A great book to read is Changing the Course of Autism, he talks a bit about twin studies.
ReplyDeleteLike I said it can't be purely genetic, just based on the fact that neither my or my husbands families has any history of autism or other developmental disorders.
Harold, you and I are completely on the same page about the cause of autism. Also wanted to say I thoroughly enjoy reading your blog, the information you put forth is fantastic.
The idea that MZ twins have the exact same genetic material is being challenged. Transcription errors and methylation differences are posited as possible reasons Environment and "chance" are given as possible for these differences.
ReplyDeleteMy daughter is profoundly autistic. We don't have any autism in the family. We do have some traits and could possibly self-diagnose ourselves as on the spectrum. However it would be very wrong to claim our social awkwardness bears any resemblance to our daughter's condition. She also suffered regression, but also had autistic traits such as a lack of social binding and social language.
Genetic diseases do not necessarily manifest themselves at birth. See Huntington's Disease as an example.
I don't reject the possibility of an environmental trigger for autism, and consider the question far from resolved..
I have a cousin with profound autism and you can read a bit about his reality here.
ReplyDeleteI think this genetic thing is only an "excuse" in order to keep many people far from the real truth.
ReplyDeleteI don't have much hope that we'll change the direction of the research without great time and effort. Economically speaking, it has occurred to many business-types, I'm sure, that this research could result in chemical bans and product recalls. It could result in environmental regulation on factories. This can't have escaped the corporate world or the political one.
ReplyDeleteI'm not a conspiracy theorist, but it seems to me that a Don Quixote or two will be required to fix the problem. My faith in the system is strong, don't get me wrong, but it will take a concerted lobby effort from families and the medical community.