biomaRt: getBM & getSequence

Question

[bsmith030465]

Hi,

I was trying to extract the exon sequence for ensembl transcript IDs (using GRCh37). I get somewhat perplexing results (getBM?):

myensembl = useMart(biomart="ENSEMBL_MART_ENSEMBL", host="grch37.ensembl.org", path="/biomart/martservice", dataset="hsapiens_gene_ensembl")

eid <- "ENST00000538028"

details <- getBM(attributes = c("chromosome_name","strand","5_utr_start","5_utr_end","genomic_coding_start","genomic_coding_end",
                                        "cdna_coding_start",
                                        "cdna_coding_end","cds_start","cds_end","3_utr_start","3_utr_end"),
                         filters = "ensembl_transcript_id",value = eid,mart = myensembl)

print(details)

seq = getSequence(id=eid, type="ensembl_transcript_id", seqType="gene_exon", mart = myensembl)
show(seq)

Am I doing something wrong in either getBM and/or getSequence?

My session info is:

> sessionInfo()
R version 3.2.0 (2015-04-16)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X 10.10 (Yosemite)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats4    parallel  stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
 [1] biomaRt_2.24.0       Biostrings_2.36.1    XVector_0.8.0        IRanges_2.2.1        S4Vectors_0.6.0      BiocGenerics_0.14.0  hash_2.2.6           stringr_1.0.0        foreign_0.8-63
[10] BiocInstaller_1.18.2

loaded via a namespace (and not attached):
 [1] XML_3.98-1.1         bitops_1.0-6         GenomeInfoDb_1.4.0   DBI_0.3.1            magrittr_1.5         RSQLite_1.0.0        stringi_0.4-1        zlibbioc_1.14.0      tools_3.2.0
[10] Biobase_2.28.0       RCurl_1.95-4.6       AnnotationDbi_1.30.1

Answer 1

[Devon Ryan]

There's nothing obviously wrong with anything you're doing. If you're curious why you're getting 7 sequences rather than 1, it's because gene_exon means "sequence of each exon within a gene". Perhaps you want cdna instead.

[bsmith030465]

Actually, I was thinking that I would get at least 7 rows from the getBM function.

[Devon Ryan]

Then you want the exon_chrom_start and exon_chrom_end attributes.

[bsmith030465]

Got it. Thanks!