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Human Genetics at IMFAR

Guest staff blogger: Vlad Kustanovich, Ph.D.

Genetic research is one of the exciting avenues of investigation that was highlighted at this year’s IMFAR meeting.  The section on human genetics started with a description of the largest study of autism twins to date. This study, described by Dr. Joachim Hallmayer, has concluded the data collection  phase and is beginning to shed new light on how much autism can be explained by genes and how much by environment.   Because identical twins share 100% of their DNA while fraternal twins share only approximately 50%, geneticists can compare the relative contribution of genes and environment, since it is assumed that for each twin pair, the environment is the same.  Clearly, both environment and genes are involved but this study may help to identify to what extent.

Dr. David Ledbetter described his effort to gather anonymous genetic information on chromosomal microarays from hundreds of thousands of patients with autism spectrum disorder and developmental delay.  He is doing this by forming partnerships with over 120 clinical labs throughout the U.S. Dr. Ledbetter, a world-reknown expert in cytogenetics, has the knowledge and respect of the scientific community to achieve the goal of creating data standards and pooling information to show which chromosomal changes are most often identified in these groups.   Deletions in regions on chromosomes 16 and 22 are identified consistently.  Although still rare, an understanding of altered genes in these regions may lead us to identify new subtypes of autism.

Other talks focused on studies of brain and face development (since these happen at the same time) in families with autism from the Autism Genetic Resource Exchange, an update from the Autism Genome Project, and a fascinating talk from Sun-Chiao Chang (working with Dr. Susan Santangelo) on sex-specific effects in autism spectrum disorder.   Ms. Chang identified several genes which seem to have an effect only in males, possibly helping to explain the common finding that there are four times as many males with autism as there females.

To read complete coverage from IMFAR, please visit http://www.autismspeaks.org/science/science_news/imfar_2010.php.

  1. Penny Massing
    May 27, 2010 at 1:16 pm

    I worked with triplets that were all on the spectrum. It is good to see that this research is being done. I always thought that families with multiples or siblings on the spectrum had to hold some key to helping figure out this mystery. A big thank you to Dr. Ledbetter for what he is doing.

  2. heather menges
    May 27, 2010 at 5:09 pm

    Great….but remember girls get it too. Genetic research probably helps contribute to how much environmental factors will effect a persons likelihood of having sensitivity to differing environmental exposure componets. So both need to be studied in a wholistic approach, for best study results! We are all out here wondering how the next generation will be helped by the Dr.’s who study to make changes for the better for all of us with medical realities to live with day in and day out!

  3. RAJ
    May 30, 2010 at 1:12 pm

    “Because identical twins share 100% of their DNA while fraternal twins share only approximately 50%, geneticists can compare the relative contribution of genes and environment, since it is assumed that for each twin pair, the environment is the same:.

    The classic twin study design assumes an equal prenatal environment is false and has led to misleading impressions and false conclusions.

    Identical twins share the same prenatal environment in 66% of pregnancies (monochorionic). A third of identical twins develop in seperate placentas (dichorionic) just like fraternal twins.

    To determine the relative contributions of genes and environment, concordance rates of identical twins need to be segregated by chorion type. If concordance rates in identical twins are the same in monochorionic and dichorionic identical twins, then the condition is largely genetic. If concordance rates in identical twins are substantially higher in monochorionic twins than dichorionic twins then the magnitude of the environmental component has been significantly understated.

    No autism twin study has ever segregated concordance rates in identical twins by chorion type.

  4. Katie Wright
    May 31, 2010 at 12:03 pm

    I appreciate the effort of these scientists but it is time to see results. This subject has been intensely studied and been the recipient of massive investments for a dozen years and still no answers.

    We have to move on. We could be studying these “rare chromosomes” for the next 50 years, meanwhile rates are rising exponetially and none of this research has prevented one child from developing autism. Let’s finally see a scientist and organization brave enough to study the rate of autism in unvaccinated sibs vs. vaccinated sibs. Such information will yield more important and immediate information than another 10 years of rare chromosomes.

    There are huge populations of unvaccinated sibs- let’s get it done.

    OMG please no more discussions of facial gazing. Enough. Millions upon millions have been invested into this. Really time to move on.

    The reason autism affects boys 5x the rate as girls is because testosterone adheres to heavy metals and the adjuvants while estrogen protects girls from the same toxic materials. Males has less protection and are more likely to suffer adverse vaccine reactions. Males w/ a family history of autoimmune disease are also 3x as likely to develop autism. W/ a weaker innate immune system their bodies go into overdrive and cannot tolerate multiple viruses at once. Instead of developing an immunity to these disease their immune system starts attacking their own GI systems and then their brain- that is a regression.The largest part of the immune system is found in the gut.

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