Genetics

Gene Studies of Autism Point to Mutations and Parents’ Age

Source: 
New York Times
Date Published: 
April 4, 2012
Abstract: 

Three teams of scientists working independently to understand the biology of autism have for the first time homed in on several gene mutations that they agree sharply increase the chances that a child will develop the disorder, and have found further evidence that the risk increases with the age of the parents, particularly the father.

IACC Releases Its 2011 Summary of Advances in Autism Spectrum Disorder Research

Source: 
IACC
Date Published: 
April 2, 2012
Abstract: 

On April 2, in honor of the fifth annual World Autism Awareness Day and HHS Autism Awareness Month the IACC has released its annual list of scientific advances that represent significant progress in the field.

With autism rising, researchers step up hunt for a cause

Source: 
USA Today
Date Published: 
April 3, 2012
Abstract: 

For many families, the quest for the causes of autism has grown more urgent with the news that the estimated prevalence of the condition grew by 23% from 2006 to 2008, a Centers for Disease Control and Prevention report said last week.

Newly Published Genetics/Brain Tissue Study Will Help Refine the Search for Specific Early Genetic Markers of Risk of Autism in Babies and Toddlers

Source: 
PLoS Genetics
Date Published: 
March 22, 2012
Year Published: 
2012
Abstract: 

A new study of autism published today in PLoS Genetics has discovered abnormal gene activity and gene deletions in the same brain region that also has a 67% overabundance of brain cells. This region – the prefrontal cortex—is involved in social, emotional, communication and language skills. The finding brings new understanding of what early genetic abnormalities lead to excess brain cells and to the abnormal brain wiring that cause core symptoms in autism. Importantly, the study also shows that gene activity abnormalities in autism change across the lifespan.

By Dr. Eric Courchesne

A new study of autism published today in PLoS Genetics (Age Dependent Brain Gene Expression and Copy Number Anomalies in Autism Suggest Distinct Pathological Processes at Young Versus Mature Ages) has discovered abnormal gene activity and gene deletions in the same brain region that also has a 67% overabundance of brain cells.  This region – the prefrontal cortex—is involved in social, emotional, communication and language skills. The finding brings new understanding of what early genetic abnormalities lead to excess brain cells and to the abnormal brain wiring that cause core symptoms in autism. Importantly, the study also shows that gene activity abnormalities in autism change across the lifespan.

The research is one of the first to focus on gene activity inside the young autistic brain, and is the first to examine how gene expression activity changes across the lifespan in autism.  It is also one of the largest postmortem studies of autism to date. This close-up look inside the brain uncovered the presence of abnormal levels of activity in genes (“gene expression”) and gene defects (deletions of portions of DNA sequences) that control the number of brain cells and their growth and pattern of organization in the developing prefrontal cortex. The abnormal gene activity occurred in several networks that are important during prenatal brain development (cell cycle, neurogenesis, DNA damage detection and response, apoptosis and survival networks). This seems to rule out a number of current speculations about postnatal causes of autism and, combined with the new evidence of a 67% excess of prefrontal brain cells, points instead to prenatal causal events in a majority of cases.

The study’s direct examination of both mRNA and DNA from the same frontal cortex region in each individual is also a unique approach to discovering the genetics of abnormal brain development in autism.  The combined mRNA and DNA results indicate that a large and heterogeneous array of gene and gene expression defects disrupt prenatal processes that are critical to early prefrontal cortex formation. “Although DNA defects vary from autistic case to case, the diverse genetic deletions seem to underlie a relatively common biological theme, hitting a shared set of gene pathways that impact cell cycle, DNA damage detection and repair, migration, neural patterning and cell differentiation,” according to the study.  Importantly, the set of functional gene pathways identified by the study’s direct analyses of autistic brain tissue are consistent with those identified by previous studies that analyzed copy number variations in living autistic patients.

A second major discovery in this study is that the pattern of abnormal gene activity changes across the lifespan in autism. Thus, in adults with autism, the study found abnormal activity in genes involved in remodeling, repair, immune response and signaling. This raises opportunities for new research directions that ask whether and how such later alterations in genetic activity impact brain structure and function.  A hope is that perhaps this later, second stage of unusual genetic activity we detected in adults with autism has something to do with enhancing adaptive connections and pruning back earlier maladaptive connections.  Further research needs to better understand the impact of those later changes in genetic activity.

Findings in the new study will help refine the search for specific early genetic markers of risk of autism in babies and toddlers.  Next steps include identifying what causes the altered genetic activity at early stages of development, when nerve cells in prefrontal cortex arise and the first steps in creating brain circuitry are being taken.  Knowledge of these specific patterns of abnormal gene activity may also give rise to future studies that search for medical interventions that target abnormal gene activity in an age-specific fashion.

New Autism Research Reveals Brain Differences at 6 Months in Infants Who Develop Autism

Source: 
Center for Autism Research at The Children's Hospital of Philadelphia (CHOP)
Date Published: 
February 17, 2012
Abstract: 

A new study from the Infant Brain Imaging Network, which includes researchers at the Center for Autism Research at The Children's Hospital of Philadelphia (CHOP), found significant differences in brain development starting at age 6 months in high-risk infants who later develop autism, compared to high-risk infants who did not develop autism.

Synaptic Mutations Increase The Risk Of Autism Spectrum Disorders

Source: 
Medical News Today
Date Published: 
February 13, 2012
Abstract: 

A new study published in PLoS Genetics uses a combination of genetic and neurobiological approaches to confirm that synaptic mutations increase the risk of autism spectrum disorders (ASDs) and underlines the effect for modifier genes in these disorders.

Mental Illness Suspect Genes Found To Be Among The Most Environmentally Responsive By NIH Study

Source: 
Medical News Today
Date Published: 
February 6, 2012
Abstract: 

For the first time, scientists have tracked the activity, across the lifespan, of an environmentally responsive regulatory mechanism that turns genes on and off in the brain's executive hub.

New Research Might Help Explain How a Gene Mutation Found in some Autistic Individuals Leads to Difficulties in Processing Auditory Cues and Paying Spatial Attention to Sound.

Source: 
Science Daily
Date Published: 
February 2, 2012
Abstract: 

New research from Cold Spring Harbor Laboratory (CSHL) might help explain how a gene mutation found in some autistic individuals leads to difficulties in processing auditory cues and paying spatial attention to sound.

Scientists Link Evolved, Mutated Gene Module to Syndromic Autism

Source: 
Science Daily
Date Published: 
January 26, 2012
Abstract: 

A team led by researchers at the University of California, San Diego School of Medicine reports that newly discovered mutations in an evolved assembly of genes cause Joubert syndrome, a form of syndromic autism.

New Research Suggests Birth Weight Plays A Role In Autism Spectrum Disorder

Source: 
Medical News Today
Date Published: 
January 23, 2012
Abstract: 

Although the genetic basis of autism is now well established, a growing body of research also suggests that environmental factors may play a role. Using a unique study design, a new study suggests that low birth weight is an important environmental factor contributing to the risk of autism spectrum disorder (ASD).