[BioC] Duplicated probesets for the same gene

[Saroj Mohapatra]

Hi all,

I have a small curiosity regarding annotation of probesets in affy GeneChips. I find that some times 2 probe sets refer to the same gene.

For example, in the HG_U95Av2, there are 2 probesets (1369_s_at and 35372_r_at) both point to the same gene IL8. I wonder what is the scientific reason for such a duplication?

I understand that the signal from 2 probesets would be affected by dye-labeling effect and hybridization effect in addition to mRNA abundance. What is then the point of having 2 probe sets which might give different results for the same gene? 

Please send any pointers/references that you find appropriate.

Thanks for your consideration.

With thanks,

Saroj