IGV-Web is a web application for exploring genomic datasets. Data can be loaded directly from a user’s local file system, or via URL from web servers and cloud providers. The application runs only in the web browser and no data is ever uploaded to the host site.
IGV-Web is developed by the same team that develops the IGV desktop application. Links to all versions of IGV can be found at https://igv.org.
IGV displays data mapped to the genomic coordinates of a reference genome. When the IGV-Web page first loads, it will load the default reference genome hg19. To load a different genome, click on the
Genome dropdown menu and either select from the list of pre-defined genomes, or use one of the options to load a genome sequence file that you specify.
Note: You must first load the reference genome, before loading data tracks. Switching genomes will clear out any loaded tracks.
The available pre-defined genomes are listed at the top of the menu. If you select any of these genomes, a corresponding gene annotation track will also be loaded.
Note: The menu includes the complete list of pre-defined genomes. Unlike IGV-Desktop, there is no
More...entry at the bottom of the menu to access a longer list.
If you have a FASTA file of your reference genome sequence, you can load it using one of the options in the bottom part of the menu:
URL option will present a dialog to enter the full web link URL to the FASTA file and to the corresponding index file. For the other options, both the FASTA file and the index file must be selected from the file chooser that pops up.
Note: A FASTA file only has the sequence data and IGV cannot display the cytoband ideogram in the chromosome ruler or automatically load a corresponding gene annotation track. You can load a gene annotation file directly via the
You will be prompted to sign into a Google account if you select the
Google Drive option, and a Dropbox account is needed for the
Developers: Another option is to create and load a .json genome file, which can include references to a cytoband file and a default gene annotation track. See the igv.js developer documentation for details on creating a reference genome object in JSON format.
To load data and genomic annotations, click on the
Tracks dropdown menu and either select from the selection of pre-defined tracks or choose one of the options to load files that you specify.
The available pre-defined track sources are listed at the bottom of the menu. Clicking on a source will open a list of datasets from that source. For example, if
ENCODE is one of the menu items, clicking on it will bring up a table of datasets available from the ENCODE data portal (Encyclopedia of DNA Elements, https://www.encodeproject.org).
See information on the available data sources.
Note: The list of pre-defined track sources varies depending on the current reference genome. Some genomes do not come with any pre-defined tracks.
To load track data from a file, use one of the options in the top part of the menu:
URL option will present a dialog to enter the full web link URL to one data file and the corresponding index file, if there is one. For the other options, a file chooser pops up and you can select files for mulitple tracks, along with the corresponding index files.
Note: For indexed files, e.g. BAM files, you must explicitly select the index file along with the data file. If you also use IGV-Desktop, you may be used to IGV automatically finding and loading the index file. This is not always possible from a web browser, so the behavior is different in IGV-Web.
You will be prompted to sign into a Google account if you select the
Google Drive option, and a Dropbox account is needed for the
See information on supported file types.
Note: Make sure to load only data files that correspond to the current reference genome. In general, a genomic data file does not include information about the genome it aligns to, which means IGV cannot automatically check if they match.
IGV-Web provides several navigation controls for specifying the genomic region to view. A ruler indicating the extent of the current region is displayed below the toolbar, and the size of the region and its genomic coordinates are displayed in the toolbar.
Select a chromosome. The chromosome dropdown menu in the toolbar includes an entry for every chromosome or contig in the current reference genome. Selecting a chromosome from the menu will set the view to include the whole chromosome. The ruler also includes a cytoband ideogram if you selected one of the pre-defined reference genomes.
allto view the whole genome, with all the chromosomes layed out side-by-side.
Enter genomic coordinates. In the text box where the genomic coordinates are displayed, you can type the coordinates of the region you want to view (e.g. chr17:41,195,312-41,278,500). The thousands separator is optional, but the chromosome name is required.
Search by gene name. In the text box where the genomic coordinates are displayed, type the name of a gene (e.g. BRCA1) and hit return or click on the magnifying glass. IGV will look up the genomic coordinates for that gene and set the viewing region accordingly. Currently for human and mouse genomes only.
Note: If your browser window is narrow, the + and - buttons appear without the slider widget.
Double-click in any of the data tracks to zoom in one level. The new view will be centered around the point where you clicked.
Click and drag in the ruler to sweep out a region to zoom into.
Click on the cytoband ideogram to move the view to that locus without changing the zoom level.
When you load a track it will be added to the bottom of the IGV track panel. To change the track order, just click on the grey grab-bar on the right edge of the track and drag it up or down to the new location.
To remove a track from the IGV browser, click on the gear icon to the right of the track and select
Remove track from the menu that pops up.
Note: Removing a track does not just hide the track. If you want to show it again you must reload the data file.
Loading a new reference genome will also delete all loaded data tracks. Refreshing the IGV-Web page in the browser will delete all loaded data and reset to the default reference genome. Or, if you launched IGV-Web from a shared URL or browser bookmark, refreshing the page will go back to the initial session state defined by the URL or bookmark.
Clicking on a track’s gear menu reveals a number of attributes. The set of attributes is determined by the type of file that was loaded into the track. For example, for a track displaying paired-end sequence alignments from a BAM file, the menu includes an option
View as pairs. In addition to
Remove track, all tracks will include the menu items
Set track name and
Set track height.
Right-clicking on a data track brings up a popup menu with actions you can perform. The set of menu items is determined by the type of file that was loaded into the track. For example, for a track displaying copy number data from a multi-sample SEG file, the menu includes an option
Sort by value, which sorts the samples by copy number value at the locus where you clicked on the track. The sort order is toggled on each selection.
When zoomed in sufficiently, the reference genome sequence track appears just below the chromosome ruler. Depending on the zoom level, the sequence is represented by colored bars: or colored letters: with adenine (A) in green, cytosine (C) in blue, guanine (G) in yellow, and thymine (T) in red.
The gear menu for sequence tracks includes two options:
Strand direction. Initially, the forward / positive strand is displayed. Click on
Reverse to flip to the reverse / negative strand. Click on
Forward to change it back.
Sequence translation. Click on
Three-frame Translate to display a 3-band track that shows a 3-frame translation of the amino acid sequence for the corresponding nucleotide sequence. The translation is shown for the current strand. Amino acids are displayed as blocks colored in alternating shades of gray. Methionines are colored green, and all stop codons are colored red. When you zoom all the way in, the amino acid symbols will appear. Click on
Close Translation to collapse the track to display the sequence only.
The sequence track cannot be removed, but it can be dragged to a different position, just like any other track.
If you load a reference genome from the list of hosted genomes provided in the
Genome menu, a special gene annotation track is also automatically loaded. For most of the hosted genomes, these annotations are from NCBI’s Reference Sequence Database (RefSeq). You cannot remove this track, but it will be automatically unloaded if you select a different reference genome.
When you load a data track, it will be positioned just above this gene annotation track. So by default, the gene annotations are always displayed at the bottom. You can however move the gene annotation track at any time by dragging it to a different position, just like any other track.
By default, the annotations are displayed in a compact mode, where overlapping transcripts are collapsed into a single line: The track gear menu provide two different options for expanding the display to show the overlapping features on separate lines:
Note: Changing the display mode does not affect the track height. A scrollbar will be added to the track if it is too short to display all the lines. To increase or decrease the track height, select
Set track heightfrom the gear menu.
IGV-Web has a number of options for saving the state of your IGV session: you can save a file in IGV session format, bookmark the page in your browser, or create a web link URL that you can share with others.
Be aware that the saved state of an IGV session includes pointers to the data files for any loaded tracks. So to fully restore the state, you must have access to the same files that were loaded when the IGV session was saved.
Note: Due to security restrictions on web browsers, if you loaded any files from the local file system, IGV cannot automatically load them for you when you restore the session even if you run the session in the same environment on the same computer where you saved the session. The IGV-Web will warn you if a restored session includes pointers to local files.
To save a file that contains the state of the current IGV session, click on the
Session dropdown menu and select
Save. In the dialog that pops up, you can set the name of the file. As noted in the dialog, the filename must have the .json suffix, or it will not be recognized as a session file when later loaded into IGV-Web. Depending on your web browser settings, the file will be saved to your default downloads folder or you will be prompted to specify a destination folder.
You can share your session with others, for example by copying the saved file to a shared file system or by uploading it to Dropbox, Google Drive, or a web server.
To restore a session from a saved file, click on the
Session dropdown menu and select one of the options in the top part of the menu:
URL option will present a dialog to enter the full web link URL to the session file. For the other options, a file chooser pops up. If you select the
Google Drive option, you will be prompted to sign into a Google account, and a Dropbox account is needed for the
Session files that were saved from the Java desktop version of IGV can also be loaded into IGV-Web via the
Session dropdown menu. However, IGV-Desktop supports more features and file types than the IGV-Web app, and so the session may not be completely restored. Also note that session files saved in IGV-Web currently cannot be loaded into IGV-Desktop.
To bookmark the current state of the IGV page in your web browser, first click on
Bookmark in the IGV-Web menu bar. This will update the URL in the browser’s address bar. Then you can use your browser to save a bookmark for the page (in most web browsers use
Command+D on MacOS,
Ctrl+D on Windows).
To restore a bookmarked session, use your browser’s mechanism for going back to a bookmarked page.
To create a web link URL that will open the IGV-Web app with all the same data tracks and settings as the current session, click on
Share in the menu bar. A dialog will pop up and display a short URL that encodes the current state of the IGV session.
COPYbutton to copy the URL to the clipboard and paste it wherever you want for safe keeping.
EMBEDbutton generates an HTML code snippet that can be used to add the session to a web page.
QR CODEbutton generates a QR two-dimenionsal barcode for the URL.
To restore a session from URL, paste it into a browser address bar, or click on the URL in an email message, tweet, etc.
Two options are provided for saving images from the IGV-Web app:
Save SVGin the app menu bar to create an image that includes all the data tracks as currently displayed, as well as the ruler and cytoband ideogram. The image file will be saved in SVG format, a scalable vector format that is useful for creating figures for publication.
Depending on your web browser settings, the image files will be saved to your default downloads folder or you will be prompted to specify a destination folder.