Friday, August 31st, 2012
You may have read recently about a study that links the age of a father with the risk for autism. While there is some real science here to report, there is also the possibility of making too much of all this. So let’s break it down.
Prior studies have suggested a link between the age of a dad and the risk for autism – as a dad’s age increases, so does the risk. The new study (published in the journal Nature) reports on a possible mechanism for this: it involves the number of genetic mutations that are passed on to a child. Click here to read a summary in the journal.
There are a few underlying ideas that are important. This line of research is showing that genetic mutations are much more frequent in a father’s sperm than in a mother’s egg. This makes sense, in that the sperm are produced throughout the lifespan in men, but women are born with their lifelong supply of egg cells. The authors of the Nature paper suggest that there is a steady increase across decades in a man’s life – so that when you are 40 you will produce more mutations than when you are 30 (and so on).
What’s the connection with autism? Well, right now it is a very indirect association. There is lots of interest in the idea that spontaneous mutations play a role in causing autism. Lots of papers have been published on this over the last few years. So the thinking here is something like connecting the dots – if spontaneous mutations are involved in the etiology of autism, and a dad’s age is a primary source of such mutations, then perhaps there is a link.
All that said, keep in mind the following:
1) The new study published in Nature did not provide any direct association between the mutations and autism
2) The assumption is that many of the mutations are harmless (and in fact somewhat normative)
3) There is, at this point, no clinical screening process to determine or suggest that a father passed on a mutation to a child
4) There are, at this point, no genetic counseling implications
Perhaps most importantly, there are lots of factors that contribute to the etiology of autism. There are certainly heritable factors that go beyond spontaneous mutations. And there are undoubtedly non-genetic factors as well.
So where are we at? At this point, spontaneous mutations are just more potential pieces of the puzzle with respect to the etiology of autism. They will continue to be researched and, hopefully, may in the future reveal more about the underlying biology of the disorder. But it’s way too early to begin to transfer the basic science into diagnostics and prevention – and too early to know what role spontaneous mutations will be shown to play in the broader context of multifactorial influences on autism.
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