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Keyword: ‘epigenetics’

Autism: I really beat the odds… But HOW???

April 15, 2010 2 comments

This post is from a Guest Blogger, Amy Kelly. Amy is a Community Outreach Liaison for the The EARLI Study in Philadelphia, PA., www.EARLIStudy.org

As a mother of three children, two boys, ages 6 and 9, and a daughter with severe autism who is 8 years old, I often wonder, how did it happen?  How did Annie get autism, and how did I beat the odds of 4:1 boys to girls that have autism and have two typical sons and a daughter who is nonverbal on the autism spectrum?  Interestingly enough my journey through autism (and ask ANY parent… it’s a journey all right) has led me to help the cause at a greater level than just my own daughter’s prognosis. I work as the Community Liaison/Outreach Coordinator for the Early Autism Risk Longitudinal Investigation (EARLI) Study.

The EARLI Study is a nationwide study that was launched last year in June 2009 across four sites in the U.S.:

1. Southeast Pennsylvania (with Drexel University and Children’s Hospital of Philadelphia)

2. Northeast Maryland (with Johns Hopkins University and Kennedy Krieger Institute)

3. Northern California (with Kaiser Permanente Northern California Division of Research)

4. Northern California (with University of California, Davis and the M.I.N.D. Institute)

Researchers are actively enrolling participants who live near the study sites. They are currently seeking 1200 women who already have a child with an autism spectrum diagnosis, and who are thinking of becoming pregnant, or who are less than 20 weeks into their pregnancy.

Both biological samples (such as blood and urine, samples from the umbilical cord, the placenta, and meconium of the new baby), and environmental samples and information (such as dust, medications, diet, medical history) will be collected. These samples and information will be analyzed to investigate:

(1) How environmental exposures during pregnancy and early life might play a role in the development of an Autism Spectrum Disorder

(2) How genetics may influence risk of Autism Spectrum Disorders – especially how genetic make-up might make certain children more vulnerable to environmental exposures

(3) Whether there are biological markers (for example, things we can easily measure in blood or urine) that will predict whether a baby eventually develops an Autism Spectrum Disorder

(4) How the behavior of newborn siblings of children with an Autism Spectrum Disorder changes over time and what behaviors might be early signs of an Autism Spectrum Disorder

Dr. Craig Newschaffer, a department chair at the Drexel University School of Public Health in Philadelphia, is the principal investigator for the study across all sites nationwide.  It is my hope that with the brilliant team of researchers and staff working on The EARLI Study, the incredible families that participate in the study, and a little bit of hope, we will one day find the causes for autism… and maybe answer my own personal question about Annie and her brothers.

For more on the EARLI study, see Early Autism Risk Longitudinal Investigation to Expand Epigenetic Studies at autismpeaks.org.

Autism in the News – Wednesday, 04.14.10

From nightmare to happy ending for parents of missing Odessa teen (Odessa, Fla.)
It was the nightmare Mary and John Parrish had long feared. Read more.

Study finds changes in fetal epigenetics throughout pregnancy (EurekAlert)
Researchers at Mount Sinai School of Medicine have found that epigenetic marks on human placentas change from the first trimester of pregnancy to the third, a discovery that may allow clinicians to prevent complications in pregnancy. Read more.

‘Walk Now for Autism Speaks’ Reception at Rentschler Field (Hartford, Conn.)
Autism Speaks Greater Hartford held a “Walk Now for Autism Speaks” kick off reception Thursday for their 5th Annual Walk at the Stadium Club at Rentschler Field in East Hartford. Read more.

Did Teen John Odgren Commit “Perfect Murder” or is Mental Disorder to Blame for High School Killing? (Woburn, Mass.)
John Odgren, charged with fatally stabbing another student at Lincoln-Sudbury Regional High School, was portrayed by a prosecutor as a calculating killer who often talked about committing “the perfect murder.” Read more.

Rescuer: ‘Lord led me’ to missing girl (MSNBC.com)
The story of how a lone volunteer working on his own found a lost girl in the Florida swamps was so extraordinary, law enforcement officials at first weren’t sure whether they should believe it. Read more.

Gene-Environment Interactions: Context Matters

March 23, 2010 3 comments

How Do Your Genes “Interact” with the Environment?

March 8, 2010 3 comments

This is a guest post by Alycia Halladay, Ph.D. Dr. Halladay is Autism Speaks’ Director, Research for Enivronmental Services.

Instead of focusing on just genetics or just environmental factors, autism researchers have been studying gene-environment interactions as possible risk factors of the disorder. A next series of posts will begin to try and explain why this is an important concept, and how it is changing the way scientists think about causes.  

Why is this concept important?  

First, in the context of risk factors, if only the separate contributions of genetics and environmental influences is calculated without considering the interaction, the proportion of the disorder that is attributable to both is underestimated. For example, environmental factors may play an important role in the development of some diseases. However, in others, the effect is only seen in susceptible individuals. Studies that examine gene-environment interactions can do the following (taken from Hunter, 2005)

  • Obtain a better estimate of the risk associated with genetic and environmental risk factors
  • Strengthen the association between environmental risk factors and disease
  • Help researchers understand the biological mechanism of disease
  • Determine which environmental factors produce risk
  • Lead to new prevention and therapeutic strategies

What does it mean?  

As most people know, genetics typically refers to the stable sequence of nucleotides on DNA strands in every cell of the human body. The nucleotides are translated to amino acids, which in turn create proteins. The amino acid sequence determines how proteins are configured, which may affect their function. Put in an oversimplistic fashion, these proteins are what affect cell function.   Some of the genetic code is inherited from both parents, and will be conferred to their children; another, more recently studied type of genetics, called epigenetics, refers to a change in protein synthesis that is not due to alterations in the DNA code. In other words, the DNA code stays the same but the way it is expressed changes. These concepts will also be discussed in a later chapter.   With regards to the term “environment”, this is a term that can refer to many “non-genetic” influences on biology and behavior. Typically when they hear “environment” people think of one of the hundreds of thousands of potential chemicals and toxins that are present in food, air and water. However, environment can also include some demographic characteristics like socioeconomic status, nutritional status and education, as well as medical procedures and illnesses, and exposure to vitamins, pharmaceuticals and/or alternative medicines. It can even refer to exposures that we may not be thinking about every day, like UV sunlight, cosmetics, food additives, and ventilation in the home.   While most people think of gene-environment interactions as an environmental risk factor producing more profound effects in a susceptible individuals, some genes may offer protection against deleterious environmental effects. Other genes may promote healthy development and their effects stifled, or even enhanced, in different environments. These concepts will be explored further in a different chapter.  

How are these interactions determined and studied? 

The best way to determine whether an interaction exists in a human population is an epidemiologic study. One of the biggest challenges is the need for large samples, or many individuals to enroll and participate. Typically, self-report measures are obtained from all participants and family members, and DNA and other biologicals are included to study DNA/RNA and level of exposure. If other measures are available such as medical records, these are also collected throughout the study. Genetic and environmental factors, and their interaction, can be studied retrospectively (after the disease has developed) or prospectively (prior to when the disease appears). Each design has strengths and weaknesses, and in many cases both approaches are taken to identify and then replicate findings. Other study designs include case-control vs. case-case. Case-control refers to studying both individuals with and without the disease. Case-case refers to studying cases (in this case individuals with autism only) both with and without different exposure levels and/or genotypes.

Autism Speaks Science Staff Reports on New Parental Age and Autism Risk Study

February 9, 2010 Leave a comment
A new study of parental age and autism risk was published online yesterday in the journal Autism Research.  The study reports on approximately 5 million births in California from 1990-1999 and reaffirmed previous data showing that parents who are older have an increased risk of having a child with autism. The study found that, regardless of the father’s age, mothers over 40 had a 51% increase in risk of having a child with autism compared with younger mothers (aged 25-29). Fathers over 40 had 36% increase in risk compared to younger fathers,  but only when the mother was in the younger range.

These numbers may sound alarming, but lets further discuss what they mean.  The 51% increase in risk for mothers over 40 can also be described as approximately 1.5 times the chances of having a child with autism compared to mothers 25-29.  In other words, the increased chance of having a child with autism was less than two-fold among this group. Thus, mother’s age and father’s age only slightly increased the risk for autism, and should not be viewed as a specific cause of autism. While the exact biological mechanism behind the relationship between delayed parenthood and ASD is unknown and warrants further investigation, it is well understood that pregnancy in older individuals is associated with higher risk for low birth weight, prematurity, and chromosomal abnormalities.  We also know that prematurity is a risk factor for autism spectrum disorders (ASD).  It also is important to keep in mind that the majority of pregnancies in older fathers and mothers are healthy.

Do changes in the ages at which parents are having children explain the dramatic increase in prevalence of ASD?  The study examined births over a decade, a period during which the prevalence of ASD has increased by over 600%.  The authors estimated that advanced maternal age only accounts for 4.6% of the increase in autism cases in California during the study period.  Thus, it is clear that, while changes in the age at which parents are having children may account for some of the increase in prevalence of autism, a large amount of the increase in prevalence remains unexplained.

As with any study, there are many methodological details to be considered.  The strength of this study lies in the large population considered. These findings reinforce other data reporting parental age is a risk factor for autism.  The study population came from the California Department of Developmental Services (DDS), which is estimated to capture about 75-80% of all “true” autism cases.  To be included in the DDS, parents had to actively seek out services.  As such, parents of autism cases in the DDS are likely to have higher levels of education and socioeconomic status, and are perhaps older than what would be found in a population-based sample. We know from this and other research that higher levels of education and sociecomic status are associated with higher rates autism (perhaps because people in this demographic category are more likely to seek diagnostic services), so it is possible that this study may overestimate the effect of parental age on autism risk. Also, it is worth noting that this study considered cases of autistic disorder only, not diagnoses from the rest of the autism spectrum.

To summarize, it is important to remember that as we dig deeper into different contributions to autism risk, we will uncover different pieces of the larger puzzle that may not seem to fit, at least at first.  Some, pieces, like this one regarding parental age, are especially intriguing because they blend biological with the socio-environmental factor of delayed parenthood.   As for biology, it is also true that as people age, modifications occur in the way the genetic code is read. This field of research known as epigenetics and is one part of the larger study of gene x environment interactions.  The topic of gene-environment interaction has been reaching our community with increasing frequency and so Autism Speaks staff and some Guest Scientists will be offering a series of blog posts specifically on these topics.  Please stay tuned. We look forward to putting this puzzle together with you.

To learn more about the recent findings in autism epidemiology, including additional findings on the effects of parental age, please see our list of the Top Ten Science Accomplishments of 2009.

Reference: Shelton JF, Tancredi DJ and Hertz-Picciotto I (2010) Independent and Dependent Contributions of Advanced Maternal and Paternal Ages to Autism Risk. Autism Research.  3: 1-10.

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