Data Viewing with VarSeq: Plotting Tracks!

         June 26, 2023

In recent weeks, GenomeBrowse capabilities have had a sudden resurgence of interest among our customers. To support this, the FAS team wanted to share with you several under-utilized GenomeBrowse plotting tricks. First, let’s cover plotting a BED file for easy track viewing. The first step is launching a GenomeBrowse window by clicking the + button and selecting GenomeBrowse (Figure 1)

Figure 1: Launch GenomeBrowse.
Figure 1: Launch GenomeBrowse.

Remember, you can always reorganize your project layout. For example, by pulling on the GenomeBrowse tab, you can reorder your view, or make GenomeBrowse its own window (Figure 2).

Figure 2: Reorganize Project.
Figure 2: Reorganize Project.

Now that GenomeBrowse is easy to view go to the Plot Button, and hit Plot a new source (Figure 3). You’ll see that there are options to plot some common sources here as well.

Figure 3: Plot a new source.
Figure 3: Plot a new source.

We are first going to plot the BED file used for calculating coverage statistics. You can quickly search by the name you gave your BED file. Here, I am searching for my file with the word ‘BED’, and now can plot that file (Figure 4).

Figure 4: Plotting the BED file.
Figure 4: Plotting the BED file.

With this view, I can look for overlap of my BED track with the RefSeq defined Exon, or any other data source plotted, such as my BAM files to visually determine the read depth in those regions I calculated coverage over (Figure 5).

Figure 5: Plotted BED track.
Figure 5: Plotted BED track.

If you have not previously associated an alignment file (BAM or CRAM file), so to File > Set Sample Fields, and you will be able to associate those alignment files by defining the path to the BAMs or CRAMs for your samples (Figure 6).

Figure 6: Set Sample Fields.
Figure 6: Set Sample Fields.

Now that the alignment file is associated, you can plot it by going to Plot > Plot Alignment for Current Sample (Figure 7).

Figure 7: Plot Alignment for Current Sample.
Figure 7: Plot Alignment for Current Sample.

Here I am viewing a BAM file, and you can see the coverage and pile-up for this region of MUC2 (Figure 8).

Figure 8: Viewing the BAM file.
Figure 8: Viewing the BAM file.

Paired with the BED file plotted above, it is easy to see the coverage region for my exon, as well as the boundaries we have defined to use with the coverage regions (Figure 9).

Figure 9: BAM file coverage compared to BED file for NRAS Exon 3.
Figure 9: BAM file coverage compared to BED file for NRAS Exon 3.

Next, lets take a look at plotting an assessment catalog. The assessment catalogs have a variety of uses, from keeping track of variants scored in VSClinical, to marking known sequencing artifacts to be filtered out of the project. Viewing an assessment catalog in GenomeBrowse can bring another dimension to your analysis. Go back to the plot button in GenomeBrowse (Figure 10).

Figure 10: Plot new source.
Figure 10: Plot new source.

At this point, you can select the drop-down option on your locally downloaded annotations to select the Assessment Catalog folder (Figure 11).

Figure 11: Select Assessment Catalogs Folder.
Figure 11: Select Assessment Catalogs Folder.

Here, we are going to select the ACMG Guidelines Variants Assessments and see if I have previously scored any variants in BRCA1 (Figure 12).

Figure 12: Select Assessment Catalog.
Figure 12: Select Assessment Catalog.

Now that the Assessment Catalog is plotted, I can hit the gear icon to determine the type of information plotted (Figure 13). Here I want to change it to Classification, but you could plot other fields like the author of the assessment, or the name of the sample with the variant.

Figure 13: Changing the visual fields.
Figure 13: Changing the visual fields.

Just like that, I can see that there is one Likely Pathogenic Variant that I have previously classified in BRCA1 (Figure 14).

Figure 14: Plotted variant catalog.
Figure 14: Plotted variant catalog.

By clicking on that variant, I can view information such as the sample’s name, the author’s name, the classification, the criteria, and more (Figure 15).

Figure 15: Viewing the assessment catalog entry for the variant.
Figure 15: Viewing the assessment catalog entry for the variant.

Now that I have pulled in information on my BRCA1 Likely Pathogenic variant, perhaps I want to see if there is any cancer-specific information about this location. To do this, I can plot CancerKB (Figure 16).

Figure 16: Plot new source.
Figure 16: Plot new source.

As before, select the annotation source of interest, hit plot, and close (Figure 17).

Figure 17: Plotting CancerKB.
Figure 17: Plotting CancerKB.

As you can see, there are multitudes of submissions for this BRCA1 location. Let’s plot the features list, so we can determine if any of the submissions are useful for this sample. Hit the Features List icon below the gear icon in the upper left-hand corner of the plot (Figure 18).

Figure 18: Plotting the features list.
Figure 18: Plotting the features list.

Examining the features list, I can look at the associated cancer type, the Tier Level for the marker, drugs, trials, and more (Figure 19)!

Figure 19: Examining the BRCA1 CancerKB features.
Figure 19: Examining the BRCA1 CancerKB features.

We hope that you can make use of these plotting tricks in your own workflows. Please reach out to support if you have any questions about how to use GenomeBrowse to complement your NGS analysis!

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