| Title | Version | Author | Date |
|---|---|---|---|
CARtool |
v1.1.3 |
Anna Odelgard, Patrik Smeds, Arielle Munters |
March 2019 |
CAR tool is a tool for assessment of per base quality of NGS data. The tool generates lists, tables and figures that can be used to evaluate coverage depth and breadth over regions of interest. CAR tool is especially created as a coverage tools for clinical use, it is a comprehensive and easy to use tool for both clinicians and bioinformatics. Multiple optional settings adapt the output based on the users’ needs with lists, tables and figures.
Example run: Coverage Analysis Report tool is launched from a terminal window. $ python CARTools.py -a myRegions.bed -b myReads.bam -c 30 50 70 -e NameOfUser -o OUTfolder OUTfilename
- Samtools – for per base coverage depth calculations.
-b: 1 BAM file with the reads-c: 3 coverage depth threshold values (for example 10 20 100)-e: Name of the person running the analysis, added to the log file-o: Output folder and name of the output files-a: 1 BED file containing the regions of interest (ROI).
The .bed file of the regions should contain chromosome, start position, end position and region name in that order. The Start position is 0-based and the end position 1-based. Additional functionality can be triggered if the (a).bed file is formatted appropriately If the first part of the bed region RegionName are the same, followed by a dot (.), regions may be merged in the report. Similarly exon and transcript information can be parsed if the following format is used: RegionName.exon.#.transcript.#.chr#...... Other words the order of the exon number and transcript must be as the order above.
-p Phred score and mapQ filtering of the bam file. Scores below the chosen values will not be used for the coverage calculation. With option (-p all value1 value2) the filtered BAM file is used throughout the analysis while (-p value1 value2) is used only for an additional column in the statistics table.
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-p: Phred score and mapQ filtering of the bam file. Scores below the chosen values will not be used for the coverage calculation. With option (-p all value1 value2) the filtered BAM file is used throughout the analysis while (-p value1 value2) is used only for an additional column in the statistics table. -
-k: Combine rows in the BED file, the rows in the bed file that has the same for example gene name will be combined and the tables and figures will be calculated on per gene information. For this option the region name must be placed first followed by a dot. -
-f: Create figures, to save time and memory the images are only generated if called. -
-s: Strand specificity, this generates two additional statistics tables one with only positive reads and one with only negative reads. All other computations are done regardless of the strand type. -
-v: Validation, creates an additional column in the statistics table. A star indicates that the gene or ROI had a coverage breadth below 95% at the first threshold value for the statistics table. This will also generate a validation list with all those genes or ROIs below 95%. -
-t: Enter a hot spot list of base pairs of interest. These positions will be pointed out in the region figure by arrows. The hot spot list should be a BED file with the columns chromosome, start, stop and region name. -
-m: Adds exon and transcript information to the mean lists. Make sure that the region name is written as follows; RegionName.exon.#.transcript.#.chr#...... Other words than exon and transcript is okay to use but the order of the exon number and transcript must be as the order above. -
-l: Enter a list of regions that are known to be low. A column in the mean short list and mean full list is added that indicate if the regions are usually low. And the table in the Region plot will have the first column in the row colored red. The input list should be a BED file with the columns chromosome, start, stop and region name. -
-d: Returns the detailed per base pair coverage list -
-i: Tailor the command sent to Samtools to calculate coverage depth. The command will end with adding the bam and bed files and saving the resulting file. Observe that Samtools uses a cut off value for the reads that effects the coverage if more reads are in the bam file. CAR tools set the cut of value to 30000.For example the default is set to be “samtools depth -a -d 30000”. This string can be changed by the user in the input followed by the flag -i. The new string is then merged with “-b theRegionsfile.bed Reads.bam and the output is saved to the correct file and folder.
Full mean list of sections below and over the first entered coverage threshold value. All base pair coverage values are evaluated for every ROI or gene and are used to create new sub regions. The sub region consists of all adjacent base pair position either above or under the threshold. For each sub region the coverage mean is calculated.
Short mean list is extracted from the full mean list. Only sub regions below the coverage threshold are saved in this shorter list. If the ROI or gene has no sub regions below the coverage threshold they will not be in the list.
Statistics table with coverage breadth values for each ROI or gene. The coverage breadth is calculated from the 3 threshold values in the input. The original statistics table is not strand specific, but if this choice is activated two additional statistical tables one for each option are generated.
Log file, a record of what files that was used, who run the analysis, used settings together with calculations of the total coverage mean value and total mean of coverage breadth values.
Validation list, list of ROIs that has less than 95% coverage in the first column of the statistics table. These are marked with stars in the statistics table if the validation option is turned on.
Strand specific tables, two additional statistics table is generated one for only positive reads and one for only negative reads. The last column in each table indicates the difference in coverage breadth.
Phred score and mapQ filtering of the bam file. The filtered coverage depths are either used for the whole analysis or only in the statistics table, added as a row under each ROI. The option, -p all value1 value2, is used if the whole analysis is to be run with the filtered bam file while -p value1 value2 only uses the filtered bam file as additional rows in the statistics table.
A pie chart of positions above or under the coverage threshold per ROI. A region plot that visualize where the coverage is lower than the threshold together with a table of the low regions name, chromosome, start position, stop position, mean and length. A bar plot with low coverage exons displayed as bars with amount of positions above or under the coverage threshold. These figured are only created if combine rows is activated.