From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Mon Aug 27 2001 - 00:53:04 MDT
Well, I suppose I must comment on this even though it brings up
a past I sometimes wish were buried....
We were working with Tom's samples 5 years ago and had worked
our way through a good number of them when it became clear
the work was problematic. Why? Because the advisors could
not agree with any certainty on how many genes there might be
and what their penetrance (force of impact) was. Without such
information doing genome scans for aging genes is like sitting
down at a Las Vegas table of poker players that you have never
seen before. You don't know if they are all schmucks from
Hicksville or the smartest card sharks west of the Mississippi.
Note carefully what is said:
"a section of 'chromosome four' that appeared to be the same
in all the old people"
Translation from science speak -- they have a genetic marker
on chromosome 4 that correlates with longevity. Genome scans
for inherited traits now probably use markers that identify
regions 5-10 megabases in size (containing multiple genes).
"believed to contain up to 10 crucial disease-fighting genes"
Since the human genome sequence is relatively complete, this
translates as "there are 10 genes within the marker region
that *could* be crucial disease-fighting genes". Probablility
that there are 10 genes or even 5 genes, I'd argue is pretty
close to zero. One, or two if they are lucky is much more
probable. Why pick the number 10? Thats the number that
we typically wrestled with because that is the number that
George Martin cited in his paper in comparing the characteristics
of diseases causing premature death with the characteristics
of aging. It doesn't have any real basis other than being an
"educated guess". As I recall the same paper estimated that up
to 70 genes could be involved in aging.
Another way of looking at this is that they only had enough
genome samples to identify one genome region at the level
of statistical significance. We were well aware of this problem
as well as the cost of obtaining such samples. If one is going
to undertake this as a commercial effort, one needs cost-benefit
tradeoffs -- how much does it cost to get a sample vs. how much
does it contribute to the information base. The lack of agreement
amongst the scientists in this area is what made this exercise
one of futility.
I'll be interested in seeing the the paper though. If a scan
of that region turns up any genes with sex-hormone related
promoters, or contains transcriptional regulatory factors, then
it will be *very* provocative and may cast some light on the
determinants of the "rate of aging".
However, it will only be the beginning of a very long quest.
Getting you a 20% boost in average longevity is only solving
a very very small part of the problem. But it may be enough
to get many people up to the singularity, so in that respect
it is good. What is bad is situation of people like James
Swayze who may not get a chance to take advantage of it
or an even larger majority of people who aren't even aware
that there may be choices available and its not all "predestined".
There are days when I simply must say:
"Damn it, Damn it all to Hell."
as unextropic as that may be.
Robert
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