[BioC] Statistics for Diagnostic Microarrays

Adaikalavan Ramasamy ramasamy at cancer.org.uk
Thu Jul 8 14:37:17 CEST 2004

Dear Mick,

I think there is a gold field of opportunities for statistics in this
field. With more and more companies advertising disease-specific chips,
there are still questions to be answers, namely :

a) gene selection : Only several hundreds or thousands of genes are
going to be selected for their discriminating ability.

b) normalisation  : The assumption that majority (90-95%) of the genes
unchanged will not hold here. If you are going to use "housekeeping"
genes, which ones to use and how to use them. So far, the main
normalisation methods (justifiably) ignore housekeeping genes as they
vary from sample to sample.

c) multiple spots : If you are going to spot, say 2000 genes, then you
can spot 10 of each at random positions on the chip. This not only
affects the normalisation (highly correlated spots) but also the
analysis aspect (is there a better approach than averaging?).

d) classification : How does one assign the probability that a patient
has a disease given the expression profile of thousands of genes. I
think we may require pattern recognition techniques or machine learning
approaches and a large enough learning set.

e) better classification : Is the diagnostic chip better than existing
tests (if any) and is it cost efficient.

Sorry for pointing out more questions than answers but I feel that more
people should be be asking these before buying/designing a designer
boutique arrays.

I think what people are currently doing is using microarrays as
filtering tool along with other knowledge to obtain a marker
gene/protien that they can easily test for. The relevant key word is

HTH, Adai.

On Thu, 2004-07-08 at 09:12, michael watson (IAH-C) wrote:
> Hi
> Obviously the greatest use for Microarrays is for gene expression
> studies, but increasingly scientists wish to use Microarrays for a
> variety of diagnostic studies, which centre more around "Is it there or
> not?" type questions rather than "How much of it is there?".  Does
> anyone know of any statistical tools or software that can be used
> specifically for diagnostic microarrays?
> Thanks
> Mick
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