From: Mitchell Porter (mitchtemporarily@hotmail.com)
Date: Tue Nov 28 2000 - 04:21:55 MST
Let's distinguish between a *gene* and an *allele*.
A gene is a DNA sequence coding for a protein. An allele is
one particular version of the sequence. Different alleles
can lead to different traits in the adult organism. A gene
may code for eye color, but it's the particular allele that
determines *which* eye color.
In discovering genes for intelligence, I'm sure that what
they've done is discovered correlation between intelligence
and allelic variation in those genes. What pro-GM parents
want are the 'intelligence alleles', i.e. the beneficial forms
of these genes.
When gene therapy is performed now, it doesn't involve alteration
of the chromosomes that contain the defective alleles. Instead,
a whole new artificial chromosome or plasmid is introduced into
the cell, containing a copy of the desirable form of the gene.
This only works a small fraction of the time, so it's done in
bulk.
With germline engineering, you're not trying to hack cells
already embedded in a body, so you can be more adventurous.
You could culture germ cells and point-mutate them over and
over, until you have the alleles you want. You could synthesize
the alleles you want and attempt to insert them directly into
the appropriate chromosomal loci. (Warning: if you do this
using splicing enzymes, rather than nanomechanically, watch
out that they don't chop up other parts of the genome too.)
But even if, by 2004, we have the technique to create human
germ cells with a specified genotype, we still won't know what
they're going to grow into. We are nowhere near being able to
predict the effects of one altered gene on the rest. Without
a major prior advance in theoretical genetics, the first human
germline engineering is going to be all about trial and error.
So I don't expect a bountiful harvest of GM babies in 2004.
If it does happen, it'll be because irrational bio-exuberance
overrode concern for the welfare of our experimental offspring.
Gene therapy in adults is a different story. It might be just
as risky, but self-experimentation will be more widely condoned
than experimentation on innocents. So by 2004 we may well have
people trying to hack their own brains via neural gene therapy,
since the technique is already available.
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