Premature Ageing

Andy Groves grovesa at starbase1.caltech.edu
Mon Mar 11 17:00:16 EST 1996


In article <4i13j9$go6 at bisance.citi2.fr>, truman at citi2.fr (J-P Truman) wrote:

> I am an immunologist by profession, so I'm not an expert on ageing. 
> However, recently I heard about children who were prematurely aged. 
> This was on TV, so I don't have any scientific facts on this. Do any of 
> you know more about this, and it's mechanisms and causes ?
> 
> Thank you in advance.

There is a condition known as Werner syndrome that causes people to age at
an accelerated rate. Sydney Shall (who used to post here occasionally) has
published tissue culture studies on samples from Werner syndrome patients.
I reproduce below an abstract from a paper of his from 1993 in PNAS v90
pp12030-12034:


"Werner syndrome is a rare, autosomal, recessive condition that is
frequently studied as a model of some aspects of human aging, although the
behavioral changes that are usually associated with old age are only seen
very infrequently. A most striking aspect of the phenotype of Werner
syndrome, presumably arising from the same gene defect, is a dramatic    
shortening of the replicative life-span of dermal fibroblasts in vitro. The
finite replicative life-span of human cells in vitro is due to the
stochastic loss of replicative ability in a continuously increasing
fraction of newborn cells at every generation. Normal human fibroblasts
achieve almost-equal-to 60 population doublings in culture, while Werner
syndrome cells usually only achieve almost-equal-to 20 population
doublings. We describe an analysis of the replicative ability of
fibroblasts from Werner syndrome patients and demonstrate that the cells in
these cultures usually exit, apparently irreversibly, from the cell cycle
at a faster rate than do normal cells, although they mostly start off with
a good replicative ability. We propose that the Werner syndrome gene is a 
''counting'' gene controlling the number of times that human cells are
able
to divide before terminal differentiation."

-- 
Andy Groves
Division of Biology, 216-76
California Institute of Technology




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