text: user2005: I am supplying to BioMart 81 ensemblIDs, but getting 80 results where 1 ensembleID: ENSMUSG00000083840 is absent. What does it mean if BioMart can not find the gene? Does it mean that it is a non-coding one or that there is just no symbol attached to it? Here is my BioMart query:
  library('biomaRt')
  mart <- useDataset("mmusculus_gene_ensembl", useMart("ensembl"))
  genes <- rownames(mat)
  G_list <- getBM(filters= "ensembl_gene_id", attributes= 
  c("ensembl_gene_id","mgi_symbol","description"),values=genes,mart= mart)
  
  
  user298: Whenever you are wondering about things like this, just look up the identifier on the Ensembl web page. If you look up ENSMUSG00000083840, you will see:
  
  This identifier is not in the current EnsEMBL database
  
  In this case, it doesn't seem to have been replaced by anything and it wasn't a protein coding gene, so it looks like it was simply a wrong annotation which has been removed. 
  
original_text: 2005: <p>I am supplying to <code>BioMart</code> <code>81</code> <code>ensemblID</code>s, but getting <code>80</code> results where <code>1</code> <code>ensembleID</code>: <code>ENSMUSG00000083840</code> is absent. What does it mean if <code>BioMart</code> can not find the gene? Does it mean that it is a non-coding one or that there is just no symbol attached to it? Here is my <code>BioMart</code> query:</p>
  
  <pre><code>library('biomaRt')
  mart &lt;- useDataset("mmusculus_gene_ensembl", useMart("ensembl"))
  genes &lt;- rownames(mat)
  G_list &lt;- getBM(filters= "ensembl_gene_id", attributes= 
  c("ensembl_gene_id","mgi_symbol","description"),values=genes,mart= mart)
  </code></pre>
   298: <p>Whenever you are wondering about things like this, just look up the identifier on the Ensembl web page. If you <a href="http://www.ensembl.org/Mus_musculus/Gene/Idhistory?g=ENSMUSG00000083840" rel="nofollow noreferrer">look up</a> <code>ENSMUSG00000083840</code>, you will see:</p>
  
  <blockquote>
    <p>This identifier is not in the current EnsEMBL database</p>
  </blockquote>
  
  <p>In this case, it doesn't seem to have been replaced by anything and it wasn't a protein coding gene, so it looks like it was simply a wrong annotation which has been removed. </p>
  