Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New genetic hypothesis for the cause of autism

08.09.2004


A mixed epigenetic and genetic and mixed de novo and inherited model may explain most cases of autism



Researchers have proposed a new hypothesis on the cause of autism, suggesting a mixed epigenetic and genetic and mixed de novo and inherited (MEGDI) model. Their hypothesis, and evidence to support it, will be published September 8, 2004 in the online edition of the American Journal of Medical Genetics Part A, and will be available via Wiley InterScience at http://www.interscience.wiley.com/journal/ajmg.

The role of genetics in autism is believed to be significant because twin studies have found that identical twins, who have the same DNA, are much more likely to share the diagnosis than fraternal twins. However, experts have not yet identified the specific genetic components related to autism, and many experts believe that multiple genes are involved.


Researchers, led by Yong-hui Jiang of Baylor College of Medicine in Houston, propose that most cases of autism can be explained by a complex model for genetic malfunction that may or may not include an altered DNA sequence. Where the DNA sequence is intact, the researchers believe that gene expression could be faulty. They suggest that some of these genetic factors are inherited, and others occur de novo in genes of the autistic person. In this study, they formulate a five-part hypothesis on the cause of autism:

Based on the evidence of parent-of-origin effects, they propose that there is a major epigenetic (related to gene expression, not sequence) component in the etiology of autism involving genetic imprinting. They suggest that epigenetic and genetic factors (both de novo and inherited) cause autism through dysregulation of two or more principal genes, one of which maps within chromosomes 15q11-q13, with the Angelman gene encoding E6-AP ubiquitin-protein ligase (UBE3A) being the strongest candidate in this region

They propose that the dysregulation of UBE3A involves some combination of overexpression, gene silencing, or misexpression of the three potential isoforms of E6-AP. They believe twin data on autism are best explained by de novo defects (epigenetic or genetic) arising in germ cells or in the embryo prior to twinning. They speculate that one or more additional genes whose function affects the role of UBE3A likely participate with the Angelman gene in an oligogenic inheritance model.

The researchers reviewed available evidence and conducted their own investigations to test elements of their hypothesis. For example, from evidence that maternal, but not paternal, inheritance of extra material from chromosome 15 causes autism in a small fraction of cases, they suggest that this chromosome, and more specifically, the gene for Angelman syndrome in this region, plays a greater role in autism than is currently appreciated. They also noted the difference in the effects of a gene depending on which parent transmits it, which strongly suggests an epigenetic effect called genomic imprinting.

The authors do not argue that their data prove the components of the oligogenic hypothesis. They say, rather, that the model is generally compatible with the data presented, it represents some fresh perspectives for autism, and it can be tested in a number of ways. "We believe that this model is highly likely to apply to some small fraction of autism cases," say the authors, "but more importantly and more speculatively, we propose that it will explain the majority of cases of autism."

The oligogenic model does not entirely rule an environmental role in autism. "The epigenetic component of the oligogenic model can be considered in the context of possible environmental factors affecting the risk of de novo imprinting defects. Non-genetic factors could affect the risk for an epigenetic form of autism," the authors conclude.

If the MEGDI model is correct for autism, it could also be relevant to other disorders, such as schizophrenia or bipolar mood disorder that clearly have a genetic component but have resisted understanding despite the completion of the human genome project.

David Greenberg | EurekAlert!
Further information:
http://www.wiley.com
http://www.interscience.wiley.com/journal/ajmg

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>