I'm currently working on hugene20sttranscriptcluster.db and realized some probe can match to multiple genes for example:
> select(hugene20sttranscriptcluster.db, '17080408', c("SYMBOL","ENTREZID"))
PROBEID SYMBOL ENTREZID
1 17080408 RAD21 5885
2 17080408 MIR3610 100500914
I was wondering if there is a specific factor that determines the order of the gene symbol ? or it's just random. If I wish to annotate the mRNA profile, would you recommend I collapse all the possible gene symbol for one probe or just use the first entry for each probe?