Full article here (no paywall):
Full article here (no paywall):
I had a quick look at the original scientific paper. They are looking at autism-associated copy number variants CNVs, where there are more copies or fewer, of particular genes or lengths of DNA. They are not looking at single nucleotide polymorphisms SNPs, or single nucleotide variants SNVs (these two are similar, except the latter disrupts the amino acid sequence in a protein and the former may not). SNPs, as far as I know, play a larger role in most people's autism than either CNVs or SNVs, which are usually described as 'rare'.
So, this study is only looking at a subset of the genetic variations that have been associated with autism, and one that is relatively rare. CNVs are found in only 5–10% of autistic people - usually those with more profound difficulties.
So, no 'cure' on the horizon, and the research is only relevant to a minority of autistic people.
Where SNPs are overwhelmingly inherited, a relatively larger proportion of CNVs occur de novo. This is where genetic deletions or duplications happen spontaneously during sperm and/or egg development. Parents without autism traits, or autism in their family history, can therefore have autistic children, and as CNVs are associated with autism with more profound difficulties, these children can be badly affected by their autism.
I have a theory that parents with hereditary autistic traits, or who are autistic themselves, are instinctively able cope with the autism of their children. Whereas the entirely allistic parents whose children are the result of de novo CNVs are not. Plus their children are likely to be more profoundly affected. This might be the behind some of the more extreme examples of 'autism mom syndrome'.
I'm not sure, if I understand your post correctly, but what I got from your reply is that the "de novo CNVs" are responsible for the profound autism that is not being inherited from parents, but the mild autism is likely to be inherited from patents. Is that then possible, that the profound and mild autism are actually two different conditions?
I think that it is down to CNVs causing more disruption to genes and gene expression than SNPs do. If you have a CNV, or more than one, that causes disruption to genes controlling neuronal function or brain development, the results are likely to be deleterious.
If you get a high dose of SNPs that individually produce small variations in gene products or gene expression, the result is likely to be less deleterious overall. Especially as many of these small variations are found throughout the general population and are likely individually to be neutral or beneficial.
Some autism-associated gene variants have also been associated with higher than average academic attainment. Most autistic people who are not profoundly disabled by their autism just get more than the average number of the autistic-associated variants that are knocking around in the general population.
There have been a couple of papers that have hinted at this, but scientists in the genetics of autism field are acutely sensitive to anything that might be misapplied or misinterpreted, so they are very careful not to draw too many overt conclusions. However, if there are two main genetic routes to autism - many small genetic variations that are found in the general population, or a small number of large genetic changes, deletions, duplications and transpositions (loss of, more copies of and movement of chunks of DNA respectively) - then it suggests to me, speaking personally, that autism is more than one condition, but one that produces some overlapping traits.
Not all CNV's are de novo, some can be inherited, but to nowhere near the scale of the common SNPs.
Thats a interesting point, is there something else going on with de novo CNV's? Is there a particular combination of these that causes a more profound response?
Good answers thanks Martin.
Thats a interesting point, is there something else going on with de novo CNV's? Is there a particular combination of these that causes a more profound response?
Good answers thanks Martin.
I think that it is down to CNVs causing more disruption to genes and gene expression than SNPs do. If you have a CNV, or more than one, that causes disruption to genes controlling neuronal function or brain development, the results are likely to be deleterious.
If you get a high dose of SNPs that individually produce small variations in gene products or gene expression, the result is likely to be less deleterious overall. Especially as many of these small variations are found throughout the general population and are likely individually to be neutral or beneficial.
Some autism-associated gene variants have also been associated with higher than average academic attainment. Most autistic people who are not profoundly disabled by their autism just get more than the average number of the autistic-associated variants that are knocking around in the general population.