The Independent reports that “Scientists have identified a genetic pattern common to people with autism that is linked to the way messages are sent in the brain”.

These findings come from a study that looked at genetic variations – alterations in the genetic code that can sometimes have serious effects on the body.

The researchers were looking at the genes affected by one specific group of rare genetic variations that had been found in 181 people with autistic spectrum disorder. Autistic spectrum disorders (ASDs) are a range of disorders that affect behaviour, social interaction and language and communication skills.

The researchers wanted to find out whether there was any relationship between the biological roles of the many different genes affected by these variations. They hoped that this might help to explain why changes to different genes could result in the same types of ASD symptoms.

The researchers found that in around half of the people the variations affected a genes or genes that could be shown to have interrelated biological roles. Many of these roles were linked to how nerve cells pass messages to each other. This suggests that some of the symptoms of ASD could be caused by abnormal signalling inside the brain.

The genetics of autistic spectrum disorders is complex, with many different genes seeming to play a role in different people. This study focused on one type of genetic variation, but other genetic variations as well as environmental factors could also contribute to ASD.

This type of study helps researchers to understand the biology and genetics of these disorders. For now, the findings do not have direct implications for the diagnosis or treatment of these conditions.

 

Copy number variations

This study was looking at what are known as copy number variations. Copy number variations are when a person has more than the usual number of copies of a piece of DNA or, alternatively, they are missing copies of a piece of DNA. These pieces of DNA can be large and can include one or more genes.

Some studies have linked copy number variations to a number of conditions such as schizophrenia, lupus and some types of lung cancer.

Where did the story come from?

The study was carried out by researchers from the University of Oxford, as well as other research centres in France, the US and Canada. It was funded by the Medical Research Council and a European Union grant.

The study was published in the peer-reviewed open-access journal PLoS Genetics.

It was covered in an appropriate way by The Independent, without any overstatement of the implications of these findings. For now, these findings largely help researchers to understand autistic spectrum disorders better. They do not currently have direct implications for the diagnosis or treatment of these conditions.

 

What kind of research was this?

This was a laboratory study looking at the genetics of autistic spectrum disorders (ASDs). ASDs are a group of disorders in which the individual’s social interaction and communication are affected.

Studies have suggested that genes play an important role in causing the conditions, but the researchers say that the genetic cause is only known in about 20% of cases.

The researchers who conducted this study hypothesised that different people with ASDs may have different rare genetic variations that contribute to their condition, but that the genes affected may all be involved in the same biological processes or pathways.

In this study they wanted to look at some of the genes that may be involved in causing ASDs to see if their biological roles are interrelated. They hoped that this would improve their understanding of the genetics and biology of ASDs.

 

What did the research involve?

The researchers were interested in a specific type of genetic variation where people have different numbers of copies of certain pieces of their DNA. These are called copy number variations or CNVs. CNVs are a type of genetic variation where people are either missing a piece or pieces of their DNA or have multiple copies of these pieces.

The researchers had information on CNVs that had been found in 181 people with ASDs in previous studies.

The researchers also used information on CNVs from a group of people without any psychiatric condition (a control group).

They did not look at CNVs that were found both in the control group and in the ASD group, as these would be less likely to be contributing to causing the ASDs.

They identified which genes were affected by these CNVs by locating them using maps of the human genome, which are long lists of the ‘letter’ sequence of the building blocks making up human DNA.

They then used a database that collects information on the effect of different mouse genetic mutations to identify what happens in mice that have disrupted versions of these genes. They did this to help them to identify what roles the genes play in the body.

They also looked at what proteins were encoded by the genes, and what other proteins these proteins interact with in the cells.

Using this information they identified what biological processes and pathways the different genes played a role in and how they were all interrelated.

They used computer programmes to come up with an interlinking map or network showing how these genes were related.

 

What were the basic results?

The researchers found that 187 genes affected by copy number variations (CNVs) could be shown to be connected in a single network of interrelated biological roles. CNVs affecting one or more of these 187 genes were found in 45% of the people with ASDs.

This network also contained 22 other genes that have previously been found to be associated with ASDs.

Many of the proteins being produced by these genes were playing roles in the transmission of electrical messages between nerve cells.

The people with ASDs who had these CNVs had an average of three CNVs within this network.

The people with ASDs who only had one CNV tended to have that CNV in a gene that was very central to the network. This was thought to indicate that the single affected gene in these cases was playing an important role.

 

How did the researchers interpret the results?

The researchers concluded that they had identified an extensive biological network of ASD-related genes. This network can show how different genes may cause ASD by affecting interlinked biological processes and pathways.

 

Conclusion

This study has identified a complex network of interrelated functions for some of the genes potentially associated with autistic spectrum disorders.

The genetics of these disorders is complex, with many different genes seeming to play a role in different people.

This study shows how these different genetic variations may result in the same group of conditions.

This study focused on one particular type of genetic variation, known as copy number variations. Other types of genetic variations may also be involved with ASD. There may also be environmental factors involved.

This type of study helps researchers to understand the biology and genetics of these disorders better.

The findings of this study do not currently have direct implications for the diagnosis or treatment of these conditions. They help to add another ‘piece to the puzzle’ of our understanding of ASDs, but the puzzle is still a long way from being fully solved.