SplitNCigarReads

Split Reads with N in Cigar

Category Read Data Manipulation

Overview

Splits reads that contain Ns in their cigar string (e.g. spanning splicing events in RNAseq data). Identifies all N cigar elements and creates k+1 new reads (where k is the number of N cigar elements). The first read includes the bases that are to the left of the first N element, while the part of the read that is to the right of the N (including the Ns) is hard clipped and so on for the rest of the new reads. Used for post-processing RNA reads aligned against the full reference.

Input

BAM file

Output

BAM file with reads split at N CIGAR elements and CIGAR strings updated.

Usage example

    gatk SplitNCigarReads \
      -R Homo_sapiens_assembly38.fasta \
      -I input.bam \
      -O output.bam

Additional Information

Read filters

This Read Filter is automatically applied to the data by the Engine before processing by SplitNCigarReads.

AllowAllReadsReadFilter

SplitNCigarReads specific arguments

This table summarizes the command-line arguments that are specific to this tool. For more details on each argument, see the list further down below the table or click on an argument name to jump directly to that entry in the list.

Argument name(s)	Default value	Summary
Required Arguments
--input -I		BAM/SAM/CRAM file containing reads
--output -O		Write output to this BAM filename
--reference -R		Reference sequence file
Optional Tool Arguments
--arguments_file		read one or more arguments files and add them to the command line
--cloud-index-prefetch-buffer -CIPB	-1	Size of the cloud-only prefetch buffer (in MB; 0 to disable). Defaults to cloudPrefetchBuffer if unset.
--cloud-prefetch-buffer -CPB	40	Size of the cloud-only prefetch buffer (in MB; 0 to disable).
--disable-bam-index-caching -DBIC	false	If true, don't cache bam indexes, this will reduce memory requirements but may harm performance if many intervals are specified. Caching is automatically disabled if there are no intervals specified.
--disable-sequence-dictionary-validation	false	If specified, do not check the sequence dictionaries from our inputs for compatibility. Use at your own risk!
--do-not-fix-overhangs	false	do not have the walker soft-clip overhanging sections of the reads
--gcs-max-retries -gcs-retries	20	If the GCS bucket channel errors out, how many times it will attempt to re-initiate the connection
--gcs-project-for-requester-pays		Project to bill when accessing "requester pays" buckets. If unset, these buckets cannot be accessed. User must have storage.buckets.get permission on the bucket being accessed.
--help -h	false	display the help message
--interval-merging-rule -imr	ALL	Interval merging rule for abutting intervals
--intervals -L		One or more genomic intervals over which to operate
--max-bases-in-overhang	40	max number of bases allowed in the overhang
--max-mismatches-in-overhang	1	max number of mismatches allowed in the overhang
--process-secondary-alignments	false	have the walker split secondary alignments (will still repair MC tag without it)
--refactor-cigar-string -fixNDN	false	refactor cigar string with NDN elements to one element
--sites-only-vcf-output	false	If true, don't emit genotype fields when writing vcf file output.
--skip-mapping-quality-transform -skip-mq-transform	false	skip the 255 -> 60 MQ read transform
--version	false	display the version number for this tool
Optional Common Arguments
--add-output-sam-program-record	true	If true, adds a PG tag to created SAM/BAM/CRAM files.
--add-output-vcf-command-line	true	If true, adds a command line header line to created VCF files.
--create-output-bam-index -OBI	true	If true, create a BAM/CRAM index when writing a coordinate-sorted BAM/CRAM file.
--create-output-bam-md5 -OBM	false	If true, create a MD5 digest for any BAM/SAM/CRAM file created
--create-output-variant-index -OVI	true	If true, create a VCF index when writing a coordinate-sorted VCF file.
--create-output-variant-md5 -OVM	false	If true, create a a MD5 digest any VCF file created.
--disable-read-filter -DF		Read filters to be disabled before analysis
--disable-tool-default-read-filters	false	Disable all tool default read filters (WARNING: many tools will not function correctly without their default read filters on)
--exclude-intervals -XL		One or more genomic intervals to exclude from processing
--gatk-config-file		A configuration file to use with the GATK.
--interval-exclusion-padding -ixp	0	Amount of padding (in bp) to add to each interval you are excluding.
--interval-padding -ip	0	Amount of padding (in bp) to add to each interval you are including.
--interval-set-rule -isr	UNION	Set merging approach to use for combining interval inputs
--inverted-read-filter -XRF		Inverted (with flipped acceptance/failure conditions) read filters applied before analysis (after regular read filters).
--lenient -LE	false	Lenient processing of VCF files
--max-variants-per-shard	0	If non-zero, partitions VCF output into shards, each containing up to the given number of records.
--QUIET	false	Whether to suppress job-summary info on System.err.
--read-filter -RF		Read filters to be applied before analysis
--read-index		Indices to use for the read inputs. If specified, an index must be provided for every read input and in the same order as the read inputs. If this argument is not specified, the path to the index for each input will be inferred automatically.
--read-validation-stringency -VS	SILENT	Validation stringency for all SAM/BAM/CRAM/SRA files read by this program. The default stringency value SILENT can improve performance when processing a BAM file in which variable-length data (read, qualities, tags) do not otherwise need to be decoded.
--seconds-between-progress-updates	10.0	Output traversal statistics every time this many seconds elapse
--sequence-dictionary		Use the given sequence dictionary as the master/canonical sequence dictionary. Must be a .dict file.
--tmp-dir		Temp directory to use.
--use-jdk-deflater -jdk-deflater	false	Whether to use the JdkDeflater (as opposed to IntelDeflater)
--use-jdk-inflater -jdk-inflater	false	Whether to use the JdkInflater (as opposed to IntelInflater)
--verbosity	INFO	Control verbosity of logging.
Advanced Arguments
--max-reads-in-memory	150000	max reads allowed to be kept in memory at a time by the BAM writer
--showHidden	false	display hidden arguments

Argument details

Arguments in this list are specific to this tool. Keep in mind that other arguments are available that are shared with other tools (e.g. command-line GATK arguments); see Inherited arguments above.

--add-output-sam-program-record / -add-output-sam-program-record

If true, adds a PG tag to created SAM/BAM/CRAM files.

boolean true

--add-output-vcf-command-line / -add-output-vcf-command-line

If true, adds a command line header line to created VCF files.

boolean true

--arguments_file

read one or more arguments files and add them to the command line

List[File] []

--cloud-index-prefetch-buffer / -CIPB

Size of the cloud-only prefetch buffer (in MB; 0 to disable). Defaults to cloudPrefetchBuffer if unset.

int -1 [ [ -∞ ∞ ] ]

--cloud-prefetch-buffer / -CPB

Size of the cloud-only prefetch buffer (in MB; 0 to disable).

int 40 [ [ -∞ ∞ ] ]

--create-output-bam-index / -OBI

If true, create a BAM/CRAM index when writing a coordinate-sorted BAM/CRAM file.

boolean true

--create-output-bam-md5 / -OBM

If true, create a MD5 digest for any BAM/SAM/CRAM file created

boolean false

--create-output-variant-index / -OVI

If true, create a VCF index when writing a coordinate-sorted VCF file.

boolean true

--create-output-variant-md5 / -OVM

If true, create a a MD5 digest any VCF file created.

boolean false

--disable-bam-index-caching / -DBIC

If true, don't cache bam indexes, this will reduce memory requirements but may harm performance if many intervals are specified. Caching is automatically disabled if there are no intervals specified.

boolean false

--disable-read-filter / -DF

Read filters to be disabled before analysis

List[String] []

--disable-sequence-dictionary-validation / -disable-sequence-dictionary-validation

If specified, do not check the sequence dictionaries from our inputs for compatibility. Use at your own risk!

boolean false

--disable-tool-default-read-filters / -disable-tool-default-read-filters

Disable all tool default read filters (WARNING: many tools will not function correctly without their default read filters on)

boolean false

--do-not-fix-overhangs

do not have the walker soft-clip overhanging sections of the reads

boolean false

--exclude-intervals / -XL

One or more genomic intervals to exclude from processing
Use this argument to exclude certain parts of the genome from the analysis (like -L, but the opposite). This argument can be specified multiple times. You can use samtools-style intervals either explicitly on the command line (e.g. -XL 1 or -XL 1:100-200) or by loading in a file containing a list of intervals (e.g. -XL myFile.intervals). strings gathered from the command line -XL argument to be parsed into intervals to exclude

List[String] []

--gatk-config-file

A configuration file to use with the GATK.

String null

--gcs-max-retries / -gcs-retries

If the GCS bucket channel errors out, how many times it will attempt to re-initiate the connection

int 20 [ [ -∞ ∞ ] ]

--gcs-project-for-requester-pays

Project to bill when accessing "requester pays" buckets. If unset, these buckets cannot be accessed. User must have storage.buckets.get permission on the bucket being accessed.

String ""

--help / -h

display the help message

boolean false

--input / -I

BAM/SAM/CRAM file containing reads

R List[GATKPath] []

--interval-exclusion-padding / -ixp

Amount of padding (in bp) to add to each interval you are excluding.
Use this to add padding to the intervals specified using -XL. For example, '-XL 1:100' with a padding value of 20 would turn into '-XL 1:80-120'. This is typically used to add padding around targets when analyzing exomes.

int 0 [ [ -∞ ∞ ] ]

--interval-merging-rule / -imr

Interval merging rule for abutting intervals
By default, the program merges abutting intervals (i.e. intervals that are directly side-by-side but do not actually overlap) into a single continuous interval. However you can change this behavior if you want them to be treated as separate intervals instead.

The --interval-merging-rule argument is an enumerated type (IntervalMergingRule), which can have one of the following values:

ALL
OVERLAPPING_ONLY

IntervalMergingRule ALL

--interval-padding / -ip

Amount of padding (in bp) to add to each interval you are including.
Use this to add padding to the intervals specified using -L. For example, '-L 1:100' with a padding value of 20 would turn into '-L 1:80-120'. This is typically used to add padding around targets when analyzing exomes.

int 0 [ [ -∞ ∞ ] ]

--interval-set-rule / -isr

Set merging approach to use for combining interval inputs
By default, the program will take the UNION of all intervals specified using -L and/or -XL. However, you can change this setting for -L, for example if you want to take the INTERSECTION of the sets instead. E.g. to perform the analysis only on chromosome 1 exomes, you could specify -L exomes.intervals -L 1 --interval-set-rule INTERSECTION. However, it is not possible to modify the merging approach for intervals passed using -XL (they will always be merged using UNION). Note that if you specify both -L and -XL, the -XL interval set will be subtracted from the -L interval set.

The --interval-set-rule argument is an enumerated type (IntervalSetRule), which can have one of the following values:

UNION: Take the union of all intervals
INTERSECTION: Take the intersection of intervals (the subset that overlaps all intervals specified)

IntervalSetRule UNION

--intervals / -L

One or more genomic intervals over which to operate

List[String] []

--inverted-read-filter / -XRF

Inverted (with flipped acceptance/failure conditions) read filters applied before analysis (after regular read filters).

List[String] []

--lenient / -LE

Lenient processing of VCF files

boolean false

--max-bases-in-overhang

max number of bases allowed in the overhang
If there are more than this many bases in the overhang, we won't try to hard-clip them out

int 40 [ [ -∞ ∞ ] ]

--max-mismatches-in-overhang

max number of mismatches allowed in the overhang
If there are more than this many mismatches within the overhang regions, the whole overhang will get hard-clipped out. It is still possible in some cases that the overhang could get clipped if the number of mismatches do not exceed this value, e.g. if most of the overhang mismatches.

int 1 [ [ -∞ ∞ ] ]

--max-reads-in-memory

max reads allowed to be kept in memory at a time by the BAM writer
For expert users only! To minimize memory consumption you can lower this number, but then the tool may skip overhang fixing in regions with too much coverage. Just make sure to give Java enough memory! 4Gb should be enough with the default value.

int 150000 [ [ -∞ ∞ ] ]

--max-variants-per-shard

If non-zero, partitions VCF output into shards, each containing up to the given number of records.

int 0 [ [ 0 ∞ ] ]

--output / -O

Write output to this BAM filename

R GATKPath null

--process-secondary-alignments

have the walker split secondary alignments (will still repair MC tag without it)

boolean false

--QUIET

Whether to suppress job-summary info on System.err.

Boolean false

--read-filter / -RF

Read filters to be applied before analysis

List[String] []

--read-index / -read-index

Indices to use for the read inputs. If specified, an index must be provided for every read input and in the same order as the read inputs. If this argument is not specified, the path to the index for each input will be inferred automatically.

List[GATKPath] []

--read-validation-stringency / -VS

Validation stringency for all SAM/BAM/CRAM/SRA files read by this program. The default stringency value SILENT can improve performance when processing a BAM file in which variable-length data (read, qualities, tags) do not otherwise need to be decoded.

The --read-validation-stringency argument is an enumerated type (ValidationStringency), which can have one of the following values:

STRICT
LENIENT
SILENT

ValidationStringency SILENT

--refactor-cigar-string / -fixNDN

refactor cigar string with NDN elements to one element
This flag tells GATK to refactor cigar string with NDN elements to one element. It intended primarily for use in a RNAseq pipeline since the problem might come up when using RNAseq aligner such as Tophat2 with provided transcriptomes. You should only use this if you know that your reads have that problem.

boolean false

--reference / -R

Reference sequence file

R GATKPath null

--seconds-between-progress-updates / -seconds-between-progress-updates

Output traversal statistics every time this many seconds elapse

double 10.0 [ [ -∞ ∞ ] ]

--sequence-dictionary / -sequence-dictionary

Use the given sequence dictionary as the master/canonical sequence dictionary. Must be a .dict file.

GATKPath null

--showHidden / -showHidden

display hidden arguments

boolean false

--sites-only-vcf-output

If true, don't emit genotype fields when writing vcf file output.

boolean false

--skip-mapping-quality-transform / -skip-mq-transform

skip the 255 -> 60 MQ read transform
This flag turns off the mapping quality 255 -> 60 read transformer. The transformer is on by default to ensure that uniquely mapping reads assigned STAR's default 255 MQ aren't filtered out by HaplotypeCaller.

boolean false