LeftAlignAndTrimVariants

Left align and trim vairants

Category Variant Manipulation

Overview

Left-align indels in a variant callset

This tool takes a VCF file, left-aligns the indels and trims common bases from indels, leaving them with a minimum representation. The same indel can often be placed at multiple positions and still represent the same haplotype. While the standard convention with VCF is to place an indel at the left-most position this isn't always done, so this tool can be used to left-align them. This tool optionally splits multiallelic sites into biallelics and left-aligns individual alleles. Optionally, the tool will not trim common bases from indels.

Input

A variant call set to left-align and trim.

Output

A left-aligned VCF.

Usage examples

Left align and trim alleles

 gatk LeftAlignAndTrimVariants \
   -R reference.fasta \
   -V input.vcf \
   -O output.vcf

Left align and don't trim alleles

 gatk LeftAlignAndTrimVariants \
   -R reference.fasta \
   -V input.vcf \
   -O output.vcf \
   --dont-trim-alleles

Left align and trim alleles, process alleles <= 208 bases

 gatk LeftAlignAndTrimVariants \
   -R reference.fasta \
   -V input.vcf \
   -O output.vcf \
   --max-indel-length 208

Split multiallics into biallelics, left align and trim alleles

 gatk LeftAlignAndTrimVariants \
   -R reference.fasta \
   -V input.vcf \
   -O output.vcf \
   --split-multi-allelics

Split multiallelics into biallics, left align but don't trim alleles, and store the original AC, AF, and AN values

 gatk LeftAlignAndTrimVariants \
   -R reference.fasta \
   -V input.vcf \
   -O output.vcf \
   --split-multi-allelics \
   --dont-trim-alleles
   --keep-original-ac

Left align variants up to 2000 bases to the left (default is at most left aligning 1000 bases to left)

 gatk LeftAlignAndTrimVariants \
   -R reference.fasta \
   -V input.vcf \
   -O output.vcf \
   --max-leading-bases 2000

Additional Information

Read filters

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

WellformedReadFilter

LeftAlignAndTrimVariants 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
--output -O	null	File to which variants should be written
--reference -R	null	Reference sequence file
--variant -V	null	A VCF file containing variants
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!
--dont-trim-alleles -no-trim	false	Do not Trim alleles to remove bases common to all of them
--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.
--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
--keep-original-ac	false	Store the original AC, AF, and AN values after subsetting
--max-indel-length	200	Set maximum indel size to realign
--max-leading-bases	1000	Set max reference window size to look back before allele
--sites-only-vcf-output	false	If true, don't emit genotype fields when writing vcf file output.
--split-multi-allelics	false	Split multiallelic records and left-align individual alleles
--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	null	A configuration file to use with the GATK.
--input -I	[]	BAM/SAM/CRAM file containing reads
--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
--lenient -LE	false	Lenient processing of VCF files
--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	null	Use the given sequence dictionary as the master/canonical sequence dictionary. Must be a .dict file.
--tmp-dir	null	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
--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 / NA

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

--dont-trim-alleles / -no-trim

Do not Trim alleles to remove bases common to all of them
If this argument is set, bases common to all alleles will not be removed and will not leave their minimal representation.

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).

List[String] []

--gatk-config-file / NA

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 / NA

Project to bill when accessing "requester pays" buckets. If unset, these buckets cannot be accessed.

String ""

--help / -h

display the help message

boolean false

--input / -I

BAM/SAM/CRAM file containing reads

List[String] []

--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] []

--keep-original-ac / NA

Store the original AC, AF, and AN values after subsetting
When subsetting a callset, this tool recalculates the AC, AF, and AN values corresponding to the contents of the subset. If this flag is enabled, the original values of those annotations will be stored in new annotations called AC_Orig, AF_Orig, and AN_Orig.

boolean false

--lenient / -LE

Lenient processing of VCF files

boolean false

--max-indel-length / NA

Set maximum indel size to realign
Maximum indel size to realign. Indels larger than this will be left unadjusted.

int 200 [ [ -∞ ∞ ] ]

--max-leading-bases / NA

Set max reference window size to look back before allele
Distance in reference to look back before allele

int 1000 [ [ -∞ ∞ ] ]

--output / -O

File to which variants should be written
Output file to which to write left aligned variants

R File null

--QUIET / NA

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[String] []

--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

--reference / -R

Reference sequence file

R String 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.

String null

--showHidden / -showHidden

display hidden arguments

boolean false

--sites-only-vcf-output / NA

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

boolean false

--split-multi-allelics / NA

Split multiallelic records and left-align individual alleles
If this argument is set, split multiallelic records and left-align individual alleles. If this argument is not set, multiallelic records are not attempted to left-align and will be copied as is.

boolean false