Highlights from Day Three: Saturday, May 17, 2008
Scientists from around the world are in London for the annual International Meeting for Autism Research (IMFAR) sharing their latest research information. The goal of those in attendance is to help individuals around the world living with autism, and their families, have a better quality of care and life.
Saturday, May 17
John Constantino, M.D., an Associate Professor of Child Psychiatry at the Washington University School of Medicine opened the final day of IMFAR with a perspective on the Broader Autism Phenotype (BAP) and the new genetics of familial and non-familial autism. With the new discoveries in molecular genetics, Dr. Constantino covered how studying the clinical, genetic, and neurobiologic features of the broader autism phenotype (BAP) present in unaffected relatives of individuals with autism will give us insight into the disorder
Family studies suggest unique patterns of aggregation of ASD features. Dr. Constantino discussed how less- or even un-affected family members might still share biological underpinnings of the disease. Focusing on these will reveal the specific causes of individual ASD traits. "Quantitative characterization of the BAP can aid in the search for core genetic and neurobiologic components of autistic syndromes," asserted Dr. Constantino. "The implications of the BAP for understanding the biology of autism are potentially profound."
Baby Siblings Research Consortium
Researchers studying infant siblings of children with autism have collaborated and shared their data to better understand the earliest manifestations of autism and how it can be treated at a very early age. In this study, a network of scientists from 11 sites across North America gathered prospective head growth data on 761 infant siblings at risk and 400 non-risk infants. Head growth was of interest because previous studies found that children with autism often display an atypical pattern of head growth characterized by normal head size at birth followed by an unusually rapid acceleration of head growth starting at about 4-6 months of age.
Their study showed that this atypical pattern of head growth differentiated high-risk infants who went on to develop autism from high-risk infants who did not develop the disorder and non-risk infants. These results suggest that monitoring head growth, which can easily be accomplished during a well-baby visit, could be an early risk marker for autism in infants who have an older sibling with autism.
Investigating Links Between Autism and the Environment
There is a lingering uncertainty around the causes of the increased autism prevalence. In a special symposia about the links between autism and the environment, a group of researchers discussed why they feel there should be a greater level of concern about the neurodevelopmental effects of chemicals.
As it relates to methodology, Irva Hertz-Picciotto, Ph.D, at University of California, Davis provided information on what types of studies have been done to determine if chemical exposures in the environment might be suspect. These include pesticides, metals, organic pollutants, virus bacteria, medical procedures and pharmaceuticals, and nutrition. A variety of retrospectively-designed studies using existing exposure databases for pesticides or air pollutants have been used, as well as population-based specimen banks.
The studies that hold the most promise are ones that use prospectively collected data from large systematic case-control studies in which each person's exposures and ultimate outcome are assessed individually. Such studies, like the CHARGE study at UC Davis, are just beginning to produce intriguing findings regarding immune dysregulation and/or pesticides in autism.
Antonio Persico, M.D., University Campus Bio-Medico, spoke about how environmental factors have been increasingly perceived as potential contributors to the pathogenesis of autism. While this has spurred interest into gene-environment interaction, the relationship has often been oversimplified, generating misunderstandings, and at times creating public alarm. Dr. Persico stressed the need for a strong, biologically-based foundation to investigations aimed at elucidating environmental contributions to complex disorders such as autism. Dr. Persico has focused much attention on the potential role of underlying autoimmune dysfunction in people with autism. As one example, he hypothesized a model for how thimerosal's known impact on calcium levels might precipitate a more abrupt onset of autism in those with immune dysfunction. However he commented that in these cases infections would also serve to trigger the autism, so such individuals could have developed autistic symptoms later anyway.
Dr. Brenda Eskenazi, from University of California at Berkeley, discussed a study in which researchers enrolled 601 pregnant women in the Salinas Valley. They measured metabolites of organic phosphate pesticides in urine collected from over 400 mothers twice during pregnancy and from children at the time of their neurodevelopmental assessments. They found that the presence of both prenatal and postnatal metabolites was associated with increased odds of mothers reporting PDD at age two. Results were similar when the children were 3.5 years old. It was suggested that children may have higher levels of pesticide exposure because they explore the environment through play, very often using hand to mouth actions.
Researchers from Tokyo Metropolitan Institute for Neuroscience presented a study on the impact of PCB (polychlorinated biphenyls) on cultured cells from the brain. They found that under these experimental conditions, PCB metabolites inhibited the formation of synapses in the cultured cells. One current theory of ASD symptoms is that they are due to abnormal neural connectivity caused by altered synapse formation during development. Therefore the researchers hypothesized that PCP metabolites pass through placenta to accumulate in the fetal brain and disrupt synapse formation. The abnormal synaptic connections may result in hetrogeneous symptoms of ASD or other co-morbid disorders.
The abnormal synaptic connections may result in hetrogeneous symptoms of ASD or other co-morbid disorders.
The Allen Institute for Brain Science in collaboration with Autism Speaks and the University of California, San Diego presented their first data from a newly announced collaboration that aims to use molecular markers to analyze brains from individuals with autism. Using both mouse and human tissue, a team of researchers led by Maureen Howell, Ph.D. has now identified gene markers of specific cortical layers and subregions of the amygdala, both of which are areas of the brain known to function abnormally in autism. Such molecular markers uniquely expressed in discrete brain regions will now allow researchers to resolve abnormalities in specific cell types within individual brain regions associated with autism.
Presentations at IMFAR may represent unpublished and preliminary data and do not necessarily reflect the position of Autism Speaks or INSAR.
View a recap of day two, Friday, May 16 here.
View the full press release for IMFAR 2008 here.