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

[Weiwei Shi]

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,

-- 
Weiwei Shi, Ph.D
Research Scientist
GeneGO, Inc.

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III