Home > Science > New findings on risk of autism in siblings – What do they mean for parents?

New findings on risk of autism in siblings – What do they mean for parents?

A message from Autism Speaks Chief Science Officer Geri Dawson, PhD

Parents of a child with autism are understandably concerned about the likelihood that their subsequent children will be affected. Autism Speaks and its legacy organization, the National Alliance for Autism Research, have been funding research on younger siblings for nearly 15 years– to help us better understand their development.

In 2003, we began organizing and co-funding a very special collaboration—the High Risk Baby Siblings Research Consortium—in partnership with Eunice Kennedy Shriver National Institute for Child Health Development.

This week, we announced the results of the consortium’s largest ever siblings study. The researchers followed younger brothers and sisters from infancy through the preschool period, when autism diagnosis becomes possible.  The study revealed a markedly higher risk among younger siblings than had been previously reported.

As the autism community absorbs the news, let me give you some background on the quality and importance of this research—and what it means for parents.

Our “Baby Sibs” researchers are an international network of clinical researchers who have been pooling information from studies of affected families in 21 sites in the US, Canada, Israel and the UK. Alycia Halladay, Autism Speaks director of research for environmental sciences, and Andy Shih, vice president of scientific affairs, have led the consortium from the start and continue to coordinate its activities.

In the study making headlines this week, the consortium researchers assessed 664 infants. Each had at least one older sibling diagnosed with an autism spectrum disorder (ASD). They found that 1 in 5 babies with an older sibling on the spectrum will likewise be affected—more than double previous estimates. The rate was higher among younger brothers—1 in 4, versus 1 in 9 for younger sisters. And autism affected nearly 1 in 3 infants with more than one older sibling on the spectrum. (Previous estimates came out of much smaller and sometimes less reliably conducted studies.)

So what does this mean for parents?

If you have an older child on the spectrum and you are concerned about your infant, talk to your pediatrician about your baby’s risk and your desire for close monitoring. And if you have any concerns about your child’s development, don’t wait. Speak with your doctor about screening.

Here are links to a number of helpful resources:

* Recent research funded by Autism Speaks shows that a one-page baby-toddler checklist can be used effectively as early as 12 months as an initial screen for autism and other developmental disorders. The screener is available here.

* The American Academy of Pediatrics has long recommended that all children be screened for autism at their 18 month well baby checkups, using the M-CHAT toddler screener, available here.

* As a parent or caregiver, one of the most important things you can do is learn the early signs of autism and understand the developmental milestones your child should be reaching.  You can see the Learn the Signs guidelines on our website, here.

* Finally, families with one or more children on the spectrum can contact their nearest “Baby Sibs” consortium researcher if they would like to participate in this important research. The list is on our website, here.

By monitoring your infant closely and promptly beginning intervention if signs of autism appear, you can ensure that your child will have the best possible outcome.

Vodpod videos no longer available.

Autism risk ‘high’ for kids with older sibling with the disorder. Autism Speaks’ Alycia Halladay, Ph.D., provides perspective of NPR’s All Things Considered. To listen to the segment, visit here.

  1. shamimp
    August 15, 2011 at 3:38 am

    What is the definition of sibling in this research? Children having the same set of parents (mother and father).

    What is the % of ASD occurence for younger step brother or step sister where they only have the same father but different mothers?

    What is the % of ASD occurence for younger step brother or step sister where they only have the same mother but different fathers?


    • m
      August 15, 2011 at 11:49 am

      I’m not sure how to use this site. Is there an answer to #1 – step siblings? Our Dr.’s answeris ‘younger sibilings ofter mimic behaviors of older sibs so not really on the spectrum.

  2. Sarah
    August 15, 2011 at 8:09 am

    Dr. Dawson –

    Please follow up on this post with a second post highlighting the rates of the NT w/issues in the younger siblings (ADHD, learning issues, anxiety, etc.). How many on of the 4 out of 5 NT (if the rate of ASD is 1:5) are truly NT (meaning a 2 or a 4 on the ADOS) and what percentage have a 6? Also, please go further and break down the NT w/issues in the 3 out of 4 NT younger brothers and the 8 out of 9 NT younger sisters.

    Secondly, I don’t know if the scope of this study covers OLDER siblings, but that would be a very interesting number as well (the percentage of truly NT older siblings vs. NT w/issues older siblings). I would suspect that the younger siblings of an ASD child would have higher rates of issues (given that the stress of having an ASD child would undoubtably affect the stress/stress/immune status of the pregnancy). My informal count of older vs. younger siblings of ASD children in our circles certainly show this.

    Third topic, please apply for some more grants for this study (and future studies) and widen the scope and take blood work noting the immune status, nutrient status, etc. of the pregnant mother, ASD child and the siblings.

    My sincere thanks.

    • Alycia Halladay
      August 16, 2011 at 10:23 am

      Hi Sarah, thank you so much for your post! I want to make sure I understand this correctly. Are you wondering about the other outcomes in those kids who were at risk but did not receive an autism diagnosis? Do they show other signs and symptoms but not meet full diagnostic criteria?

      The answer is sometimes yes. Last year a study by one of the BSRC researchers showed that of those not diagnosed with autism, 20% had an autism-like language problem. Early identification of these problems, including signs of ASD, should be monitored very closely for referral to the most appropriate intervention service. Parents should make sure that their doctors and clinicians know of their concerns and any signs they see (or don’t see)


      • Sarah
        August 17, 2011 at 6:35 am

        Hi Dr. Halladay –

        Yes and thank you.

        So, in the three year evaluation “NT group” – 1:5 had language problems.

        Do you have the percentages for anxiety rates? ADHD rates?

        Further question re: this group: which subjects do you plan to follow past the age of three? Only the NT w/issues siblings or all of the NT siblings? And, for how long?

        Our NT w/issues sibling is enrolled with your consortium and will be enrolled forever (or until funding on aging-baby-sibs runs out).


    • Sarah
      August 17, 2011 at 7:01 am

      Drs. Dawson & Halladay –

      Thinking more about the numbers and “the environment.” I really do think it is a good idea to recruit older siblings of newly diagnosed ASD children (a different funding stream but at the same institutions). Ultimately, you’ll be able to compare all the NT w/issues rates in the siblings (if they are the same for older and younger NT siblings). My guess would be that the rates would be far different. I guarantee my younger child had the most hostile, cortisol on speed dial, sleep deprived pregnancy on the planet (and ultimately a deprived immune system/compromised pollutant filter). Your numbers of the NT w/issues and environmental impacts will have much more validity with the older sibling numbers.

      Of course, please widen the scope in your baby-sib studies for biological markers as well.

      Thank you.

      • brenda
        August 19, 2011 at 2:06 am

        Excellent suggestion and set of observations, Sarah. We are of the “If I knew when what I know now” generation. I have two boys with autism, 8 and 15. My 15 year old was diagnosed last year. That’s a lot of lost time. I see what you are doing and it is very important.

  3. Jennifer Alger
    August 15, 2011 at 9:40 am

    I was adopted and when I had my first child 21 yrs ago, Autism was extremely difficult to get a diagnosis, My second son, the doctor thought we were being overly paranoid,He then got his diagnosis! I had a daughter and no signs whatsoever! My third son was born and he was diagnosised! I finally got some history on my bio. family and it turns out that every male on my side of the family had either mental retardation or now autism! My daughter refuses to have children for fear that it will be a male! We have had genetic testing and they could not find any link between them! All of our boys have straight autism diagnosis, not just on the spectrum! Is there any way to test if my daughter would be a carrier like I was?

  4. August 15, 2011 at 9:44 am

    Many parents stop having children after one is diagnosed. We did but the second one was already here. Yes, they both have it but on different ends of the spectrum. I suppose if we continued having children they all would have it. The prevalence among families is so high. This is also why my BFF and I tell our high-functioning ASD kids they are cousins, so they will not get romantically involved :)

  5. Amy Lerner
    August 15, 2011 at 10:01 am

    is there any research regarding the risk of unaffected siblings and their chance of having their own children on the spectrum

  6. August 15, 2011 at 10:21 am

    To follow up on Sarah’s last point: The EARLI study (www.EARLIstudy.org) is now recruiting families near its 4 US research sites — 2 in California, one in Maryland, one in Pennsylvania. EARLI enrolls families who have a child on the autism spectrum (PDD-NOS, Aspergers and autism) and who are currently pregnant — or considering a future pregnancy. EARLI looks at genetic and environmental influences, and takes biological samples and dietary data, among other information.

    I work in Maryland for this study (which is funded federally and by Autism Speaks) because I have two sons, a 10-year-old who is typical and a 7-year-old who is on the spectrum. In addition to making a contribution to science, EARLI participants can be reassured that their babies will be clinically assessed through the study until age 3, giving parents a chance to seek early intervention if a developmental delay is suspected. Families also will be compensated for their cooperation, up to a total $605 over four years.

    I hope this information is useful to families!– Michelle Landrum

    • Sarah
      August 17, 2011 at 11:31 am

      Too bad the EARLI study isn’t at all the ATN and/or baby-sibs sites. But, Michelle – this is truly thrilling. How I wish I had your job. :)

  7. Andrea
    August 15, 2011 at 10:35 am

    My older son was digonosed with autism and i just recently had another boy who is three months old with a different father. I have often wondered throughout my pregnancy if this will effect him as well. What about younger siblings with a different mother or father? What was the percentage on that?

    Thank you

  8. Angel
    August 15, 2011 at 10:47 am

    I was wondering have there been any studies on boy/ girl premie twins. My children are were such and my son (the older of the twins) was diagnosed with aspergers just before his 12th birthday and his sister was not breathing the first couple minutes of life. Does she just have learning difficulties due to the lack of oxygen or could she also be on the spectrum? My twins are now 15years old. I would love some answers! Did my son’s diagnosis get missed earlier on because they were getting services because of their prematurity??? Please Help!!!

  9. Kathleen
    August 15, 2011 at 10:49 am

    Any studies done on the children of normal siblings? My daughter whose younger brother has high functioning autism. She is anxious about the possibility of autism in any children she has. She has no children so far. Thank you.

    • Kevin
      August 15, 2011 at 7:10 pm

      To Kathleen:

      If this helps any, there are 4 of us in our family. All of us are in our mid to late 40s. Both of my brothers (one older, one younger) are Autistic with Mental Retardation. My sister (the oldest of us 4) has 4 lovely, healthy, “normal” daughters. I think the best advice my mother gave us was: Have children, don’t worry about numbers or statistics, love them all equally and give them all the support you can give.

  10. Mom S.
    August 15, 2011 at 11:17 am

    After finding out that our son (firstborn) was on the Spectrum, we stopped trying to conceive another child for the fear of the unknown. We had read the chances of having more children on the spectrum were increased. We both would have loved to have more children, however, we did not want to have another child go through what our son has. It’s been a long and tiresome road with therapies (some every hour on the hour when he is awake) over the past 8 years (and still going). But it has been worth every moment, step and effort we have put into helping our son. He is in a mainstream classroom, in Cub Scouts and plays sports. I am happy we decided not to have another child so our focus was on helping our son on the spectrum and giving him the attention that he needed to become the person he is today. This study just supported that the decision that we made years ago was the right one for us. Thank you!

  11. August 15, 2011 at 11:23 am

    At Brain Balance, we’ve long contended that both autism and ADHD (as well as other neurobehavioral disorders) have in common an underlying connectivity issue between and within the two sides of the brain. Brain Sync continues to be discussed in research circles as an issue in these disorders. You can read our article on brain sync and autism here:

    Brain Balance Centers
    Where every child connects with success

  12. Jennifer D
    August 15, 2011 at 11:46 am

    I was also wondering about younger siblings from different parents. My first child is on the spectrum, I am now divorced and engaged to someone else. My ex and I went for genetic testing for my son but it came out as him just being different. My fiance hasn’t had any kids yet and we are worried about having one.

    Thank You.

  13. August 15, 2011 at 1:12 pm

    Hi All,
    These are all GREAT questions. So we’re getting Alycia Halladay to host a live web chat this afternoon to answer your questions. You can link up via a special tab on the Autism speaks Facebook page (left hand column). Here’s a link: http://www.facebook.com/autismspeaks?sk=app_234155463293127.


  14. Katie Wright
    August 15, 2011 at 2:02 pm

    We need a study of vaccinated and and unvaccinated sibs.
    My second son had terrible colic, horrible reflux and was labelled “failure to thrive.” I had to feed him with an eye dropper all day long. He also had bad vaccine reactions.
    It was awful, actually worse than w/ his older ASD brother as a baby.

    In a state of panic after my older son’s dx I stopped vaccinating. Within months my second son became a different baby. Now he is thriving and NT. We are really lucky and know it is not as simple as this the vast majority of the time. But full sibs share 50% of their DNA. That is huge! It stands to reason if 1 has a negative reaction to an environmental toxin the other will as well.

    Think about it. None of us have autism- autism, autism- not aspergers. 99% of people w/ moderate to severe autism do not reproduce. These numbers should be falling not climbing!

    • Sarah
      August 15, 2011 at 3:01 pm

      Right there with you Katie.

    • August 15, 2011 at 5:21 pm

      Hi, Katie. Alycia replies: “These investigators are looking at a number of things that happen during pregnancy and infancy that may influence the development of autism. To learn more about this study, follow this link to the EARLI STUDY.” (http://www.earlistudy.org). Katie, we also answered your question on the live web chat. Thanks.

    • Kevin
      August 15, 2011 at 7:17 pm

      100 % of the claims of the “link” between vaccinations and autism have been proven to be FALSE! I’ve been dealing with this absolute nonsence for the last 4 decades! There is NO LINK!

    • Barbara Johnson
      August 16, 2011 at 9:21 am

      Hi Katie! We also stopped vaccinating the younger sibling at the suggestion of our DAN doctor, as she was starting to display speech and motor delays. She’s now considered NT . . . but I shudder to think what would have happened had we continued to vaccinate. Chelation has brought her older brother off the spectrum, along with other biomedical interventions.

      Why why why do we have to keep begging for the obvious study to be done — vax’d vs. un-vax’d?

  15. Casey
    August 15, 2011 at 2:25 pm

    Here is what I have been doing in Pittsburgh with my family!! I am VERY worried with having my second boy and him having autism this is why I do the study!!!


  16. melissa
    August 15, 2011 at 4:09 pm

    the new findings in the siblings study indicate that genetics play a more influencial role in family autism than previously thought. Would this suggest that environmental factors are less of an issue? I have a 5 yo diagnosed with autism and a new 4 month old. If we have the genetics for passing autism genetically, could I influence our new child (weather she manifests autism later) by stearing clear of environments triggers?

  17. RAJensen
    August 15, 2011 at 5:12 pm

    Autism is associated with birth complications so the recurrance risk shouldn’t be any great surprise. Autism is been shown in several studies to be associated with pre term birth and pre-eclampsia for example;

    Recurrance risks for pre-term delivery is highest (57%) in women with two prior pre term deliveries. Recurrence risk, which is affected by the frequency, order, and severity of prior preterm births with a 57% recurrance risk for women with 2 prior very preterm deliveries (21-31 weeks).

    The risk of recurrent preeclampsia in pregnancy is inversely related to gestational age at the first delivery: 38.6% for 28 weeks’ gestation or earlier, 29.1% for 29-32 weeks, 21.9% for 33-36 weeks, and 12.9% for 37 weeks or more.

    Familial autoimmune disorders which can be transmitted to the fetus in pregnancy is also associated with very high risk for autism and high recurrance risks. Pregnancy problems associated with maternal auto-immune disease include prenatal maternal urinary tract, upper respiratory, and vaginal infections and in the newborns asphyxia; prematurity, and seizures are more common in the autistic group.




  18. August 15, 2011 at 6:33 pm

    Hi everyone,
    We tried to answer as many of your questions as possible during the live webchat with Alycia today. The transcript will be posted! Thanks.

  19. Sarah
    August 15, 2011 at 7:18 pm

    and how might that fact the Sanford researchers recently said environment plays a significant role fit into this sibling study? Could a common toxic exposure be involved that si poisoning these siblings?

    To say there is a higher rate of autism among siblings tells only part of the story. The picture won’t be complete until,we look at common routes of exposure to toxins and yes, that includes vaccines and other medicines those siblings recieved and where those products were manufactured (ie. country of origin).

    Look at food and medicine sources and track back to where they were made. Were these products made in the US or overseas? There may be a problem in the manufacturing, quality control issue that results in these siblings being exposed to common toxins.

  20. Katie Wright
    August 16, 2011 at 8:55 am

    Dear Jessica,

    I think this is a very important discussion AS is having.
    However, it is important to note that although we know a few risk factors, taken together they are still a small %. Even worse almost nothing can be done to prevent preterm delivery despite a mother’s absolute best efforts. Same w/ multiples- what can a mom do- selective reduction is not what most would even consider.

    So basically this is totally frightening news and yet again we have no way to prevent autism- other than stop having children. This is so depressing. However, I think it is great AS is being frank w/ their audience, you cannot hold back this information.

    All the more reason AS must redouble their efforts and rather than just measuring ASD numbers get directly to environmental causation. As AS recently found AS is 50% environmental. We cannot do anything to change our genes so lets figure out what is going wrong in our environment now.

  21. EV
    August 16, 2011 at 12:28 pm

    Interestingly, pre-eclampsia is now considered to be the result of an autoimmune condition.
    There seems to be a strong pattern of maternal autoimmunity, Hg sensitivity and autism.
    More studies are needed in this direction.

  22. William Schini
    August 17, 2011 at 8:42 pm

    Our oldest son is on the ASD, born in 2001 with galactosemia. We had fraternal twins in 2008; perfectly healthy, no ASD signs for either siblings. Case study, maybe?

  23. brenda
    August 19, 2011 at 1:54 am

    I went to the infant/toddler website and was completely thrown off. It needs to be easier to navigate for new exhausted mothers and fathers. They cannot function at this level at this stage of development as parents. I have two boys with autism, 8 and 15, but would not have been able to access the test due to the difficulty. Please consider this comment and amend! :)

  24. Lucy
    August 19, 2011 at 3:25 pm

    My one grandson has ASD. He is now 23 years old. Have they done any studies on the children of austic children. If he finds the right woman,I don’t know if we could or should try to talk him out of having his own children. He is very high functioning but he has a 3rd cousin who is very severely autistic.

  25. August 20, 2011 at 7:57 am

    I’m going to believe, now, that autism is more of a genetic condition than environmental? I hope so because I’ve had a hard time believing that it a disorder caused by antidepressants taken during pregnancy, or, prenatal condition such as gestational diabetes, paternal age and maternal age. Thank you. I hope we’re close to finding a cause. It’s hard to believe we haven’t found a cause yet.

  26. A. Miller
    August 20, 2011 at 4:30 pm

    I’m still not sold on this, I have four children and my two oldest sons are not on the spectrum. My youngest son is diagnosed with ASD and I also have a two year old daughter and She has been diagnosed with PDD due to speech delays.

  27. jenwileman
    August 20, 2011 at 8:18 pm

    Hi, My child was in the study , I have 6 children. My oldest son has autism and my younger 3 sons have no neurological problems at all. Neither do my 2 daughters. Please remember as environmental factors also can exacerbate genetic ones, those with the diagnosis should look into ways to make changes for future children. I realize this is difficult if you received the original diagnosis while siblings were still very young. But our results may give hope to others. These results still need to be looked at further.

    Did all siblings receive all vaccinations per schedule, mine have not.

    Have mothers taken any further steps to support there pregnancy. I did.

    Support families with autism, don’t scare them.

  28. forrest
    August 20, 2011 at 10:43 pm

    daughter of sib with severe autism, she has borderlile ADHD. Wondering what risk is for her offspring? she’s hitting childbearing age, so it’s a concern.

  29. forrest
    August 20, 2011 at 11:07 pm

    I should mention they are both adopted, different Dads, same mom, not much history available.

  30. forrest
    August 21, 2011 at 12:53 pm

    ok, I understand autism & ASD, what is NT? I just know I’ll be inundated for asking!!

    • Sarah
      August 22, 2011 at 4:31 pm

      Neurotypical (meaning normal brain development). http://en.wikipedia.org/wiki/Neurotypical Likely coined by a mother who was dealing with her husband – who couldn’t handle when she said things like, “what normal children are doing.” HIS child is normal!!! lol :). I’m joking. I have no idea who came up with the term, but I like my explanation. My husband hates using “normal children” and can actually handle the neurotypical term.

  31. August 21, 2011 at 10:09 pm

    Our son is four years old now but we are concerned that he may have Asbergers or Autism. He has several developmental delays including lack of potty training and speech. Upon birth, he joined our world grey in color and his father thought he was still born. We know that it was a dry birth due to several trips to the ER where we were sent home thinking it was false labor. This was obviously not the case. Could this have caused these diseases?

    • momof2asd
      August 29, 2011 at 9:38 pm

      Autism is not a disease, and it is quite possible that your son has a developmental disablility because he is four you will have a difficult time getting state services to cooperate..I would take him to a professional to have him evaluated.

  32. August 30, 2011 at 3:09 pm

    I didn’t say it was a disease. I am an early childhood educator and realize we are still finding answers on autism. Evaluation tomorrow. If a doctor could answer our privies question that would be great.

  33. October 3, 2011 at 10:01 am

    Thanks for all the great info here. I will be back to read some more soon.

  1. August 15, 2011 at 8:01 am
  2. August 15, 2011 at 11:37 am
  3. August 15, 2011 at 2:19 pm
  4. August 16, 2011 at 10:41 am
  5. August 16, 2011 at 12:18 pm
  6. August 16, 2011 at 12:56 pm
  7. September 6, 2011 at 12:21 pm
  8. September 28, 2011 at 4:36 pm
  9. February 2, 2012 at 5:20 pm

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: