[BioC] biomaRt : multiple entrezgene ids to one affy id?

[Steffen Durinck]

Hi Weiwei,

It looks like Ensembl has mapped these three entrezgene ids to the same 
transcript.
You'll have to mail to the Ensembl helpdesk to ask why this is and to 
see if there is a possible error.
You can reach them at:  helpdesk at ensembl.org  they are usually very 
quick to respond.
Explain them what you did and what the output is (they are not familiar 
with the R syntax).

regards,
Steffen

Weiwei Shi wrote:
> Dear all:
>
> Here is some piece of output from my query:
>
>   
>> mart=useMart(biomart="ensembl", dataset="hsapiens_gene_ensembl")
>>     
> Checking attributes and filters ... ok
>
>   
>> getBM(attributes=c("affy_hg_u95a", "entrezgene","ensembl_transcript_id"), filters="affy_hg_u95a", values="31330_at", mart=mart)
>>     
>   affy_hg_u95a entrezgene ensembl_transcript_id
> 1     31330_at       6223       ENST00000221975
> 2     31330_at     728953       ENST00000221975
> 3     31330_at     731572       ENST00000221975
>
> I do not understand why there are multiple entrezgene ids
> corresponding to one affy id. Did I miss something here?
>
> Thanks,
>
>