By Carlos curated from -

Gene hunt is on for mental disability : Nature News

Let me qualify the sensationalist headline a bit. There’s probably not just any one gene that can be found to qualify someone as mentally disabled when mutated, however, what they’re talking about here in Nature is a program launched in the UK that aims to identify mutations in genes different from the already known genetically based mental disorders, like Down’s syndrome (Trisomy 21) and Fragile X Syndrome.

It turns out that there’s a class of mental disability found in children that isn’t attributable to the common genetic abnormalities, and also don’t have an environmental component as with fetal alcohol syndrome for instance. It is the hope of the researchers that by sequencing the exomes (translated gene regions) of these children, and by comparing them with their parents’, the mutations that are most likely responsible for their intellectual disability will pop out. Perhaps they’ll find single gene mutations of interest, but I’m not too optimistic about that.

Hopefully though, such findings will open up more channels of research and lead to avenues of therapeutic intervention.  My concern though, as it is with any study or hunt for single targets, is that with medical geneticists and their tools getting more & more refined, the ills of the eugenics movement may begin to surface and we’ll have difficult ethical issues to confront. Does a genetic screen for such abnormalities give credence to early abortions ?

Fodder for the philosophers and social scientists, no doubt, but the real-world consequences of such genetic tools and the information brought about are racing toward us like a speeding freight train, forcing some us to brace for the impact before we can see the train clearly.

What will we allow with the identification of new intellectual disability gene targets? Can a single gene mutation spell inevitable intellectual disability, or will we discover compensatory mechanisms at work? With about 1000 genes responsible for the normal function of the human brain, is there hope for our science to work out all of the genetic interactions? If not, then what are we doing this for anyway, right ?

About 2% of children experience some form of intellectual disability. Many have disorders such as Down’s syndrome and fragile X syndrome, which are linked to known genetic abnormalities and so are easily diagnosed. Others have experienced environmental risk factors, such as fetal alcohol exposure, that rule out a simple genetic explanation. However, a large proportion of intellectual disability cases are thought to be the work of single, as-yet-unidentified mutations.

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