Contact: to feature here

Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Epigenetics Linked to Autism
Epigenetics is the study of how DNA expression is controlled. DNA is stored by being wrapped around proteins called histones. The histones have different arms that can be modified, normally by the addition of a methyl group, a phosphate group, or an acetyl group. When specific points on the histone arms are modified, the DNA is either more tightly wound around the histone, which results in decreased gene expression, or the DNA is opened up, resulting in increased gene expression. Epigenetics can help explain why individuals with the same genes may have different expression patterns. Epigenetic changes may even be heritable, meaning they can be passed from parent to offspring. The changes caused by the different histone modifications can be induced by environmental factors. In addition, the changes may be reversible, although scientists have not fully discovered how to do this in cells.

Autism spectrum disorder is a series of disorders associated with symptoms involving difficult social interactions, repetitive behaviors, and impaired language development. Different patients that have been diagnosed with autism have varying levels of severity of the disease, and may present with different symptoms in the three affected areas. The incidence of autism spectrum disorder has increased significantly in recent years. This may be in part due to improved diagnostic standards, and a larger range of symptoms included in diagnosis. Indeed, many patients who have been diagnosed with Autism in recent years would not likely have been diagnosed many years ago due to the different standards.

A genetic component has been associated with the development of autism spectrum disorders. A major piece of data supporting the hypothesis that Autism spectrum disorders have a genetic component comes from data from identical twins. If one identical twin has autism spectrum disorder, the other twin has a 70% chance of also having autism spectrum disorder. However, this also means that if one identical twin has Autism spectrum disorder, there is a 30% chance that the other twin does not. This implies some type of environmental or non-genetic component to the disease.

Researchers from King’s College London examined DNA histone methylation at 27,000 sites in the genome from fifty sets of identical twins. Methylation of the histone proteins generally results in decreased expression of the DNA. Out of the fifty sets of twins studied, eleven pairs were both healthy, five pairs both had autism spectrum disorder, and the remaining thirty four pairs had different autism spectrum disorder diagnoses. The research team found patterns they were able to link to both the diagnosis of autism spectrum disorder as well to the severity of the disease. In all of the patients that had an autism diagnosis, specific sites in the DNA had histone methylation. In addition, different symptoms of autism spectrum disorder were linked to methylation at specific sites of the genome. Some of these sites occurred at locations associated with early brain development and the development of autism spectrum disorder, which may be contributing factors to autism.

The research into epigenetic modifications at specific locations in the genome is a big breakthrough in autism research. Because some of the epigenetic histone modifications can be influenced by environmental pressures, this research helps bridge the gap between a genetic cause of autism spectrum disorder and an environmental cause. This information could help improve diagnosis of autism spectrum disorder, helping clinicians find more definitive data in determining their diagnoses. Clinicians could diagnose autism earlier in some patients, or perhaps even find interventions to help delay the progression of the disorder. Early diagnosis and therapy for autism spectrum disorder results in better outcomes for the patients. In addition, because epigenetic changes may be reversible, it is possible that researchers might find ways to help reduce the symptoms associated with autism. While scientists do not fully understand exactly how histone modifications occur, or what causes them, research is constantly advancing and this information may one day be available. If scientists can manipulate the genes affected by histone modification in autism, they might be able to provide therapeutic benefits in this manner as well. The research linking specific epigenetic histone methylation to autism symptoms and disease severity indeed will be followed by many groundbreaking advancements in autism research. With the rising incidence of autism, these advancements will be very welcome to many parents and patients alike.

Like Post Reply
Autism and mitochondrial dysfunction

The previous article highlighted the complex nature of autism-spectrum disorders and the interactions of genetics and environment that play a part in their development. Autism-spectrum disorders are a complex and heterogeneous set of disorders with different causes and likely different degrees of genetic and environmental influences.

At the level of the cell, interaction between the genetics of the cell and its environment are partially mediated by mitochondria. Autism-spectrum disorders are linked to defects in neurodvelopment. Neurodevelopment is highly dependent on energy and it has been demonstrated in various recent studies that mitochondrial dysfunction is a feature of some autism-spectrum disorders.

In a study of 2 to 5 year old children participating in the Childhood Autism Risk From Genes and Environment study in California, it was confirmed that children with autism were more likely to have mitochondrial dysfunction, mtDNA overreplication, and mtDNA deletions than non-autistic children.

One way in which mitochondrial dysfunction could contribute to autism-spectrum disorders would be via abnormal brain bioenergetics. Another study confirmed that in brain tissues from the anterior cingulate gyrus, motor cortex, and thalamus of autism patients in the Autism Tissue Program, USA, there were alterations in expression of several genes associated with mitochonrial dysfunction in brainregions of autistic subjects.

One role of mitochondria is to synthesise mitochondrial ATP and other mitokines that communicate with neighbouring cells via purinergic signaling. This conveys messages to these cells about cellular health or danger signals. In a study of a poly(IC) mouse model of autism spectrum disorders, it was found that treatment with suramin, which is a purinergic antagonist, corrected several multisystem abnormalities that are used to define autism-spectrum disorder phenotype in this mouse model.

Clearly mitochondrial dysfunction is emerging as another element of the complex genetic background of autism-spectrum disorders. Difficulty in accessing brain samples for autism-specific disorders has led some researchers to consider other accessible nonbrain resources which could be used in biomarker identification. Gene array studies in lymphoblastoid cell line-derived RNAs from have suggested potential changes in the alternative splcing of transcripts in autism compared with controls, for example in CYFIP1, a previously reported autism susceptibility gene. These kinds of studies are of vital importance in helping us get to the heart of the biological basis of autism.


ANITHA, A. et al., 2013. Downregulation of the expression of mitochondrial electron transport complex genes in autism brains. Switzerland: International Society of Neuropathology.

ANITHA, A. et al., 2012. Brain region-specific altered expression and association of mitochondria-related genes in autism. England: BioMed Central.

GIULIVI, C. et al., 2010. Mitochondrial dysfunction in autism. JAMA: The Journal Of The American Medical Association, 304(21), pp. 2389-2396

NAVIAUX, R.K. et al., 2013. Antipurinergic therapy corrects the autism-like features in the poly(IC) mouse model. Plos One, 8(3), pp. e57380-e57380

TALEBIZADEH, Z., ALDENDERFER, R. and WEN CHEN, X., 2013. A proof-of-concept study: exon-level expression profiling and alternative splicing in autism using lymphoblastoid cell lines. Psychiatric genetics
Like Post Reply

Possibly Related Threads…
Last Post
Replies: 3
Views: 17,174
09-19-2013, 03:50 AM
Last PostAlyssa03
Replies: 1
Views: 12,306
09-18-2013, 11:14 PM
Last Postmtwalsh01
Replies: 0
Views: 8,863
12-03-2011, 02:54 AM
Last Postshalinibalan

Users browsing this thread:
1 Guest(s)

Epigenetics Linked to Autism00