Genetics

Age Alters Patterns of Chemical Tags on Sperm DNA

Source: 
Simons Foundation Autism Research Initiative
Date Published: 
August 18, 2014
Abstract: 

The configuration of methyl tags that modify DNA in sperm change as men get older, according to a study published PLOS Genetics. These alterations may help explain why children of older fathers are at increased risk for neuropsychiatric disorders such as autism. Researchers at the University of Utah collected sperm from 17 men, once in the 1990s and again in 2008. They found that the distribution of methyl tags, a particular kind of DNA modification, shows relatively consistent changes over time in the sperm. However, the study does not necessarily prove that these altered patterns survive past fertilization or influence the risk of disorders such as autism.

Disruptive CHD8 Mutations Define a Subtype of Autism Early in Development

Source: 
Cell
Date Published: 
July 7, 2014
Abstract: 

A variation in the CHD8 gene has a strong likelihood of leading to a type of autism accompanied by digestive problems, a larger head and wide-set eyes, a study in Cell reports. This discovery is part of an emerging approach to studying the underlying mechanisms of autism and what those mean for people with the condition. Many research teams are trying to group subtypes of autism based on genetic profiles. This is the first time researchers have shown a definitive cause of autism from a genetic mutation.

Large Study Underscores Role of Gene Copy Number in Autism

Source: 
Simons Foundation Autism Research Initiative
Date Published: 
June 2, 2014
Abstract: 

People with autism tend to carry mutations that duplicate or delete several genes at once, according to a large study published in the American Journal of Human Genetics. Previous studies have shown that people with autism have more large deletions or duplications of DNA, also known as copy number variations (CNVs), than controls do. The new study, the largest to look at CNVs in people with autism thus far, confirms this finding. It also found that in people with autism, the CNVs are more likely to affect genes linked to intellectual disability and fragile X syndrome.

Coexpression networks implicate human midfetal deep cortical projection neurons in the pathogenesis of autism

Source: 
Cell
Date Published: 
November 21, 2013

"As techniques for studying the human genome have advanced, an increasing number of genes are being associated with ASD; it is important to find the connections between these ASD-linked genes in order to understand how they may contribute to ASD. A new resource called the BrainSpan1 atlas provides researchers with three dimensional maps showing when and where genes turn on and off in the human brain, from embryonic stages through older adulthood. This study used the BrainSpan atlas to identify commonalities in when and where ASD-associated genes are expressed.By using the shared characteristics of different gene mutations implicated in ASD, this study creates a picture of the developmental processes that are changed in these cases. This image provides a sharper focus for the development of targeted treatments, and even holds potential for the development of personalized interventions based on genotype."

Mothers of Children with Autism Share Their Sensory Problems

Source: 
Simons Foundation Autism Research Initiative
Date Published: 
May 2, 2014
Abstract: 

A small study published 3 April in Molecular Autism found that 98 percent of mothers of children with autism have unusual responses to sensory stimuli, including light, sound and touch. Up to 90 percent of children with autism show sensory problems, fixating on or avoiding certain smells, sounds or textures. As a result, the newest edition of the Diagnostic and Statistical Manual of Mental Disorders lists abnormal sensitivity in one or more of the five senses as a core diagnostic feature of autism. It’s unclear whether genetics contributes to these sensory patterns, but a larger study examining the relationship between unusual sensory response, autism traits and additional disorders in family members may clarify the link.

Repeats in Human DNA may Aggravate Autism Symptoms

Source: 
Simons Foundation Autism Research Initiative
Date Published: 
April 21, 2014
Abstract: 

Certain DNA repeats that increased exponentially during human evolution are directly related to the severity of autism symptoms, according to a preliminary study published in PLoS Genetics. The repeats each span 65 amino acids and are collectively referred to as DUF1220, for ‘domain of unknown function.’ There are six types of these repeats, each with a slightly different sequence and all of which diverged from a common ancestor.

Patches of Disorganization in the Neocortex of Children with Autism

Source: 
New England Journal of Medicine
Date Published: 
March 26, 2014
Abstract: 

New evidence suggests that autism begins in the brain before birth when brain cells fail to develop properly. In this study, the abnormalities in the brain cells were not uniform, showing autism's wide range of symptoms and severity. This better understanding of prenatal development of the brain cells of people with autism underscores the importance of early identification and intervention.

New Technique Finds Mutant Cells in a Haystack

Source: 
Simons Foundation Autism Research Initiative
Date Published: 
March 19, 2014
Abstract: 

Researchers have developed a method to isolate a single mutant cell from thousands of others, they reported in the March issue of Nature Methods. The new approach will allow researchers to precisely engineer and study human cells without altering the genome. Ultimately, the method could be used to alter an individual’s cells before returning them to his or her body.

A Higher Mutational Burden in Females Supports a “Female Protective Model” in Neurodevelopmental Disorders

Source: 
American Journal of Human Genetics
Date Published: 
February 27, 2014
Abstract: 

Researchers have more clues as to why more boys than girls are diagnosed with Autism Spectrum Disorder. A new study in the American Journal of Human Genetics suggests that for boys, it takes less of a genetic hit to cause autism than it does for girls. The study continues to say that when it does appear in girls, it is due to a much more severe genetic hit, usually resulting in much more severe autism symptoms.

Induced Neuron Cell Line Resembles Immature, Healthy Neurons

Source: 
Simons Foundation Autism Research Initiative
Date Published: 
February 12, 2014
Abstract: 

A commercially available line of neurons generated from induced stem cells would serve as a good control for autism research, according to a study published in Psychopharmacology. Characterizing these neurons in detail shows that they express most of the genes linked to autism and look like typical, albeit immature, cells. Induced pluripotent stem cells, or iPSCs, are skin or blood cells reverted to a state from which they can become any cell in the body. Researchers can use the technique to turn cells from people with a neuropsychiatric disorder into neurons. They can then compare the neurons with those from controls to gain understanding of the disorder.