Hi, 

The TxDb.Mmusculus.UCSC.mm10.knownGene package appears to be giving me some strange co-ordinates for certain genes, making them huge, e.g. this microRNA which stretches 35 Mb according to the txdb package but 66 bp according to UCSC. Any suggestions/something I'm overlooking?

library(TxDb.Mmusculus.UCSC.mm10.knownGene)
txdb <- TxDb.Mmusculus.UCSC.mm10.knownGene
genes <- genes(txdb)
subset(genes, width(genes) > 35000000)

Output:

GRanges object with 1 range and 1 metadata column:
            seqnames               ranges strand |     gene_id
               <Rle>            <IRanges>  <Rle> | <character>
  102465114    chr19 [24942236, 60774397]      - |   102465114
  -------
  seqinfo: 66 sequences (1 circular) from mm10 genome

Session info:

R version 3.3.1 (2016-06-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.1 LTS

locale:
 [1] LC_CTYPE=en_GB.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_GB.UTF-8    
 [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_GB.UTF-8   
 [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C       

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

other attached packages:
 [1] BiocInstaller_1.24.0                    
 [2] TxDb.Mmusculus.UCSC.mm10.knownGene_3.4.0
 [3] GenomicFeatures_1.26.0                  
 [4] AnnotationDbi_1.36.0                    
 [5] Biobase_2.34.0                          
 [6] GenomicRanges_1.26.1                    
 [7] GenomeInfoDb_1.10.1                     
 [8] IRanges_2.8.1                           
 [9] S4Vectors_0.12.0                        
[10] BiocGenerics_0.20.0                     

loaded via a namespace (and not attached):
 [1] XVector_0.14.0             zlibbioc_1.20.0           
 [3] GenomicAlignments_1.10.0   BiocParallel_1.8.1        
 [5] lattice_0.20-33            tools_3.3.1               
 [7] SummarizedExperiment_1.4.0 grid_3.3.1                
 [9] DBI_0.5-1                  Matrix_1.2-7.1            
[11] rtracklayer_1.34.1         bitops_1.0-6              
[13] RCurl_1.95-4.8             biomaRt_2.30.0            
[15] RSQLite_1.1                Biostrings_2.42.0         
[17] Rsamtools_1.26.1           XML_3.98-1.5   

Thanks,

Mark

By definition, the gene extent is the start of the 'first' transcript to the end of the 'last' transcript. For non-coding RNA species, which may be found multiple places on a chromosome, this has the unintended effect of returning a really long gene that doesn't really exist. If you did

txs <- transcriptsBy(TxDb.Mmusculus.UCSC.mm10.knownGene)

txs["102465114"]

You sill see that there are two transcripts for this miRNA, spaced quite far apart on chr19.