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Tero Toivanen

Research on the genomics of autism from the Center for Biom - 0 views

www.theautismnewswire.com/NewsITems.aspx

research autism genomics genes DNA gene alterations brain development nerve signaling

shared by Tero Toivanen on 19 Mar 11 - No Cached
  • Research on the genomics of autism from the Center for Biomedical Informatics at The Childrens Hospital of Philadelphia indicated that several genes and genomic variants contribute to autism. The gene alterations are rare but when they are in play, they seem to disrupt genes that are significantly involved in brain development and nerve signaling.
  • According to the September 15, 2010 issue of Science Translational Medicine, males with certain DNA alterations to their X-chromosome are at high risk of having autism.
  • This research was performed at the Centre for Addiction and Mental Health (CAMH) and The Hospital for Sick Children (SickKids), in Toronto Canada.
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  • One percent of boys with autism involved in the study had mutations in the PTCHD1 gene on the X-chromosome. No boys without autism showed this mutation.
  • Girls who also had this mutation did not seem to exhibit autistic traits. It appears that girls may be protected from developing autism because they have a second X-chromosome.
  • Still these girls could be carriers, passing on the mutation to their children. Their sons could then have autism.
  • Certain rare genetic variants were found 20 percent more in children with autism than in other children. Researchers also discovered new disruptions, where a child of non-autistic parents had autism.
  • t appears that some children have private genetic mutations not passed on genetically, and this leaves them more susceptible to autism. Interestingly, each child showed a different disturbance in a different gene.
  • Researchers hope to gain more information as they identify groups of disrupted genes. Ultimately they hope to be able to develop treatments for autism.
Tero Toivanen

Mutations in 3 Genes Linked to Autism Spectrum Disorders - 1 views

www.theautismnewswire.com/NewsITems.aspx

genes linked autism spectrum disorders research

shared by Tero Toivanen on 08 Apr 12 - No Cached
  • Mutations in 3 Genes Linked to Autism Spectrum Disorders : Mutations in three new genes have been linked to autism, according to new studies including one with investigators at Mount Sinai School of Medicine
  • The findings, in a trio of papers revealing new genetic targets in autism, are published in the April 4th online issue of the journal Nature.
  • The genes with mutations identified in the studies – CHD8, SNC2A, and KATNAL2 – were discovered with a new state-of-the-art genomics technology known as exome sequencing, where all protein coding regions of the genome, called the exome, are analyzed.
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  • The researchers say that with further characterization of the genes and sequencing of genes in thousands of families, they will be able to develop novel therapeutics and preventive strategies for autism.
  • The institutions involved in this study sequenced data from more than 500 families (both parents and the affected child), examining the protein-enriched areas of the genome.
  • “When the same mutations are found in multiple affected children and none are found in children without autism, we believe that we have identified mutations that collectively affect a higher proportion of individuals with autism,” said Dr. Buxbaum. “Our studies revealed that the proteins encoded by the mutated genes interact with each other far more than expected, demonstrating significantly greater connectivity than would be expected.”
Tero Toivanen

NeuroLogica Blog » The Genetics of Autism - 0 views

www.theness.com/neurologicablog

autism genetics

shared by Tero Toivanen on 03 May 09 - Cached
  • What this means is that there is likely to be a complex set of many factors that contribute to ASD - not one single cause.
  • The same exact situation is true for other entities, like schizophrenia and attention deficit disorder (ADD).
  • One difference, however, is that schizophrenia and ADD likely represent changes to particular parts of the brain, while autism is likely due to changes in the global architecture of the brain.
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  • Getting back to the genetics of autism, current models are therefore consistent with what is being found when the genetics of autism is researched - researchers are finding many genes that predispose to autism in a subset of cases but no single or simple universal cause. At present, 133 different gene variants have been linked to autism.
  • This new research, conducted by Dr. Hakon Hakonarson of the Children’s Hospital of Philadelphia, is a genome wide analysis involving about 10,000 individuals.
  • The results are especially significant because the variants lie between two genes, called CDH9 and CDH10, which are known to play an important role in forming nerve connections in the brain.
  • The gene variants that correlated with ASD are for proteins that are involved in the process of neurons forming connections with each other. There is already other lines of evidence that suggest what is different in ASD brains is a decrease in the amount of interconnectedness and communication among neurons. It is therefore likely no coincidence that this study found genetic correlations for proteins involved with neuronal connections.
  • This also is compatible with the finding that many separate genes are potentially involved with ASD - for there are many separate genes and processes involved with forming and maintaining neuronal connections.
  • Tero Toivanen on 03 May 09
     
    A new genome-wide analysis of families with autism has found significant gene associations, adding to the growing evidence for strong genetic contribution to autism.
Tero Toivanen

Autism disorders might be reversible. | - I Teach Autism.com - - 0 views

www.iteachautism.com/...-or-disorder-may-be-reversible

autism fever epigenetics locus coeruleus brain neurobiology LC-NA system theory Albert Einstein College

shared by Tero Toivanen on 08 Jun 09 - Cached
  • Scientists at Albert Einstein College of Medicine of Yeshiva University have proposed a sweeping new theory of autism that suggests that the brains of people with autism are structurally normal but dysregulated, meaning symptoms of the disorder might be reversible.
  • The central tenet of the theory, published in the March issue of Brain Research Reviews, is that autism is a developmental disorder caused by impaired regulation of the locus coeruleus, a bundle of neurons in the brain stem that processes sensory signals from all areas of the body.
  • The new theory stems from decades of anecdotal observations that some autistic children seem to improve when they have a fever, only to regress when the fever ebbs.
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  • Einstein researchers contend that scientific evidence directly points to the locus coeruleus–noradrenergic (LC-NA) system as being involved in autism. “The LC-NA system is the only brain system involved both in producing fever and controlling behavior,” says co-author Dominick P. Purpura, M.D., dean emeritus and distinguished professor of neuroscience at Einstein.
  • The locus coeruleus has widespread connections to brain regions that process sensory information.
  • It is also involved in a variety of complex behaviors, such as attentional focusing (the ability to concentrate attention on environmental cues relevant to the task in hand, or to switch attention from one task to another).
  • “What is unique about the locus coeruleus is that it activates almost all higher-order brain centers that are involved in complex cognitive tasks,” says Dr. Mehler.
  • Drs. Purpura and Mehler hypothesize that in autism, the LC-NA system is dysregulated by the interplay of environment, genetic, and epigenetic factors (chemical substances both within as well as outside the genome that regulate the expression of genes). They believe that stress plays a central role in dysregulation of the LC-NA system, especially in the latter stages of prenatal development when the fetal brain is particularly vulnerable.
  • Drs. Purpura and Mehler believe that, in autistic children, fever stimulates the LC-NA system, temporarily restoring its normal regulatory function.
  • the future of autism treatment probably lies in drugs that selectively target certain types of noradrenergic brain receptors or, more likely, in epigenetic therapies targeting genes of the LC-NA system.
  • “You can’t take a complex neuropsychiatric disease that has escaped our understanding for 50 years and in one fell swoop have a therapy that is going to reverse it — that’s folly. On the other hand, we now have clues to the neurobiology, the genetics, and the epigenetics of autism. To move forward, we need to invest more money in basic science to look at the genome and the epigenome in a more focused way.”
  • Tero Toivanen on 08 Jun 09
     
    Scientists at Albert Einstein College of Medicine of Yeshiva University have proposed a sweeping new theory of autism that suggests that the brains of people with autism are structurally normal but dysregulated, meaning symptoms of the disorder might be reversible.
Tero Toivanen

What Do New Genetic Findings Mean to Families with Autism? - 0 views

autism.about.com/...an-to-families-with-autism.htm

autism genetics research

shared by Tero Toivanen on 02 May 09 - Cached
  • reply from lead researcher Hakon Hakonarson:
  • The variant we detected at the 5p14 locus (common variant) has been present for a long time in the genome (most likely since man moved out of Africa) and this region is highly conserved between species which means that it is regulating gene expression and gene function (the CHD10 gene being the most critical one).
  • We know that the association is strongest in those individual who have the greatest abnormalities in social skills/interactions and those that show least interest in interactions; we have not detected any other characteristics yet, but we keep working on it.
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  • Once we learn about this difference, we can then look for medications that block the consequences of the variant and once we make sure they are safe, we can then start testing these new medications in children who are at risk of developing autism, with the objective of preventing autism (i.e., avoid breakdown in connections between nerves and abnormality in brain connectivity).
  • Response: Yes, all of them could be tested in utero; we have identified 10 new variations (9 rare and 1 common) and we have replicated (and confired) four other once that were previously published (neurexin 1, contactin 4, 15q11 and 22q11). However, we do not have a yes or no answer as to whether the fetus will be autistic -- but if we are testing a fetus in an autistic family the value of the test is much higher.
Tero Toivanen

New Theory Of Autism Suggests Symptoms Or Disorder May Be Reversible - 0 views

www.sciencedaily.com/...090401145312.htm

autism new theory brain

shared by Tero Toivanen on 02 Apr 09 - Cached
  • the brains of people with autism are structurally normal but dysregulated, meaning symptoms of the disorder might be reversible.
  • autism is a developmental disorder caused by impaired regulation of the locus coeruleus, a bundle of neurons in the brain stem that processes sensory signals from all areas of the body.
  • The new theory stems from decades of anecdotal observations that some autistic children seem to improve when they have a fever, only to regress when the fever ebbs.
  • ...11 more annotations...
  • This study documented that autistic children experience behavior changes during fever.
  • Einstein researchers contend that scientific evidence directly points to the locus coeruleus–noradrenergic (LC-NA) system as being involved in autism. "The LC-NA system is the only brain system involved both in producing fever and controlling behavior," says co-author Dominick P. Purpura, M.D., dean emeritus and distinguished professor of neuroscience at Einstein.
  • The locus coeruleus has widespread connections to brain regions that process sensory information. It secretes most of the brain's noradrenaline, a neurotransmitter that plays a key role in arousal mechanisms, such as the "fight or flight" response. It is also involved in a variety of complex behaviors, such as attentional focusing (the ability to concentrate attention on environmental cues relevant to the task in hand, or to switch attention from one task to another). Poor attentional focusing is a defining characteristic of autism.
  • "What is unique about the locus coeruleus is that it activates almost all higher-order brain centers that are involved in complex cognitive tasks," says Dr. Mehler.
  • autism, the LC-NA system is dysregulated by the interplay of environment, genetic, and epigenetic factors
  • They believe that stress plays a central role in dysregulation of the LC-NA system, especially in the latter stages of prenatal development when the fetal brain is particularly vulnerable.
  • a higher incidence of autism among children whose mothers had been exposed to hurricanes and tropical storms during pregnancy.
  • autistic children, fever stimulates the LC-NA system, temporarily restoring its normal regulatory function. "This could not happen if autism was caused by a lesion or some structural abnormality of the brain," says Dr. Purpura.
  • future of autism treatment probably lies in drugs that selectively target certain types of noradrenergic brain receptors or, more likely, in epigenetic therapies targeting genes of the LC-NA system.
  • If the locus coeruleus is impaired in autism, it is probably because tens or hundreds, maybe even thousands, of genes are dysregulated in subtle and complex ways," says Dr. Mehler. "The only way you can reverse this process is with epigenetic therapies, which, we are beginning to learn, have the ability to coordinate very large integrated gene networks."
  • "You can't take a complex neuropsychiatric disease that has escaped our understanding for 50 years and in one fell swoop have a therapy that is going to reverse it — that's folly. On the other hand, we now have clues to the neurobiology, the genetics, and the epigenetics of autism. To move forward, we need to invest more money in basic science to look at the genome and the epigenome in a more focused way."
  • Tero Toivanen on 02 Apr 09
     
    the brains of people with autism are structurally normal but dysregulated, meaning symptoms of the disorder might be reversible.
Tero Toivanen

New Study: Autism has Multiple Genetic Roots | Suite101 - 3 views

suite101.com/...multiple-genetic-roots-a246721

autism research study

shared by Tero Toivanen on 10 Nov 12 - No Cached
  • The study’s major finding was that children with ASD have significantly more CNVs affecting their genes than children without ASD. Children with ASD have 20 percent more CNVs in general, and 70 percent more CNVs impacting genes known to be associated with ASD or cognitive problems. Significantly, many of the genes that are affected control important functions such as cell proliferation and cell-to-cell communication.
  • Some of the newly discovered genetic variants are inherited, and are found in parents or siblings of children with them. Others, however, seem to have originated spontaneously in the affected child, and do not appear in other family members.
  • While these findings add significantly to the scientific understanding of the genetic and biological underpinnings of ASD, the immediate usefulness is limited. That’s because there are a very large number of CNVs, and each child shows a different pattern of genetic changes. Each of these changes is rare; no CNV showed up in more than one percent of the children studied.
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  • “This will lead to a paradigm shift in understanding the etiology of autism,” says Stephen Scherer, a senior scientist at The Hospital for Sick Children in Toronto, Canada. “Until now, most scientists thought individuals with autism shared common genes. We now think each person has his own rare variations.”
  • If significant CNVs show up, behavioral treatment can be started early. That has been shown to improve children’s outcomes significantly. “If we provide stimulation early, while the brain is still plastic, we can improve cognitive development, social interaction and communication,” says Geri Dawson, Chief Science Officer of Autism Speaks, the major sponsor of the research project.
  • What this new research suggests is that autism and ASD probably result from the interaction between many different genes and a child’s environment. Rather than search for one single cause and one “magic bullet,” researchers will try to find as many significant genetic variants as possible, link them to the biological functions and pathways they control, and then search for medications that can improve or normalize the functioning of damaged pathways.
Tero Toivanen

NIMH · Our brains are made of the same stuff, despite DNA differences - 1 views

www.nimh.nih.gov/...-despite-dna-differences.shtml

nimh brains dna differences gene prefrontal cortex schizophrenia autism research study genetic variation neuroscience neurons

shared by Tero Toivanen on 30 Oct 11 - No Cached
  • “Having at our fingertips detailed information about when and where specific gene products are expressed in the brain brings new hope for understanding how this process can go awry in schizophrenia, autism and other brain disorders,” said NIMH Director Thomas R. Insel, M.D.
  • Among key findings in the prefrontal cortex:Individual genetic variations are profoundly linked to expression patterns. The most similarity across individuals is detected early in development and again as we approach the end of life.Different types of related genes are expressed during prenatal development, infancy, and childhood, so that each of these stages shows a relatively distinct transcriptional identity. Three-fourths of genes reverse their direction of expression after birth, with most switching from on to off.Expression of genes involved in cell division declines prenatally and in infancy, while expression of genes important for making synapses, or connections between brain cells, increases. In contrast, genes required for neuronal projections decline after birth – likely as unused connections are pruned.By the time we reach our 50s, overall gene expression begins to increase, mirroring the sharp reversal of fetal expression changes that occur in infancy.Genetic variation in the genome as a whole showed no effect on variation in the transcriptome as a whole, despite how genetically distant individuals might be. Hence, human cortexes have a consistent molecular architecture, despite our diversity.
  • Among key findings:Over 90 percent of the genes expressed in the brain are differentially regulated across brain regions and/or over developmental time periods. There are also widespread differences across region and time periods in the combination of a gene’s exons that are expressed.Timing and location are far more influential in regulating gene expression than gender, ethnicity or individual variation.Among 29 modules of co-expressed genes identified, each had distinct expression patterns and represented different biological processes. Genetic variation in some of the most well-connected genes in these modules, called hub genes, has previously been linked to mental disorders, including schizophrenia and depression.Telltale similarities in expression profiles with genes previously implicated in schizophrenia and autism are providing leads to discovery of other genes potentially involved in those disorders.Sex differences in the risk for certain mental disorders may be traceable to transcriptional mechanisms. More than three-fourths of 159 genes expressed differentially between the sexes were male-biased, most prenatally. Some genes found to have such sex-biased expression had previously been associated with disorders that affect males more than females, such as schizophrenia, Williams syndrome, and autism.
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  • Our brains are all made of the same stuff. Despite individual and ethnic genetic diversity, our prefrontal cortex shows a consistent molecular architecture.
  • Males show more sex-biased gene expression. More genes differentially expressed (DEX) between the sexes were found in males than females, especially prenatally. Some genes found to have such sex-biased expression had previously been associated with disorders that affect males more than females, such as schizophrenia, Williams syndrome, and autism.
  • Tero Toivanen on 30 Oct 11
     
    Our brains are all made of the same stuff. Despite individual and ethnic genetic diversity, our prefrontal cortex shows a consistent molecular architecture. 
Tero Toivanen

The Genetics of Autism (ActionBioscience) - 1 views

www.actionbioscience.org/...dougherty.html

autism genetics savant

shared by Tero Toivanen on 08 Apr 09 - Cached
  • Despite this relatively high frequency, scientists do not understand the mechanism of this serious developmental problem. What they have discovered is that autism is one of the most heritable mental disorders known. In other words, autism appears to be largely genetic in origin, and most autistic children inherit the disorder from their parents.
  • In the case of PKU, geneticists have determined that retardation is due to genetics (a mutated phenylalanine hydroxylase gene) and the environment (a phenylalanine-containing diet).
  • In the case of autism, the likelihood that the sibling of an affected child also would be affected is between three and six percent.
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  • Nonetheless, this incidence is about 100 times greater than the rate at which autism affects unrelated people in the population.
  • One study showed that the likelihood that the identical twin of an autistic child also would be autistic was 82 percent, whereas the equivalent rate for fraternal twins was only 10 percent.
  • With sophisticated statistical techniques and numerous twin studies, behavioral geneticists now believe that as much as 90 percent of the behavioral phenotype of autism is related to inherited genes.
  • Tero Toivanen on 08 Apr 09
     
    With sophisticated statistical techniques and numerous twin studies, behavioral geneticists now believe that as much as 90 percent of the behavioral phenotype of autism is related to inherited genes.
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