Dear All,
I am using BAM files for chip-seq analysis. The chromosome notation in a usual BAM file is like: chr1. In my file the chromosomme notation is 1. Is there a way to change that in the BAM file? For further analysis it is very important to change the notation.
Many thanks!
Greetz Lisanne
The following line works well for me. It will replace the names of chromosome 1 to 22, X, Y and MT (mitochondrial DNA). It will create a new file with the name test_chr.bam instead of test.bam.
use Samtools
samtools view -H test.bam |\
sed -e 's/SN:1/SN:chr1/' | sed -e 's/SN:2/SN:chr2/' | \
sed -e 's/SN:3/SN:chr3/' | sed -e 's/SN:4/SN:chr4/' | \
sed -e 's/SN:5/SN:chr5/' | sed -e 's/SN:6/SN:chr6/' | \
sed -e 's/SN:7/SN:chr7/' | sed -e 's/SN:8/SN:chr8/' | \
sed -e 's/SN:9/SN:chr9/' | sed -e 's/SN:10/SN:chr10/' | \
sed -e 's/SN:11/SN:chr11/' | sed -e 's/SN:12/SN:chr12/' | \
sed -e 's/SN:13/SN:chr13/' | sed -e 's/SN:14/SN:chr14/' | \
sed -e 's/SN:15/SN:chr15/' | sed -e 's/SN:16/SN:chr16/' | \
sed -e 's/SN:17/SN:chr17/' | sed -e 's/SN:18/SN:chr18/' | \
sed -e 's/SN:19/SN:chr19/' | sed -e 's/SN:20/SN:chr20/' | \
sed -e 's/SN:21/SN:chr21/' | sed -e 's/SN:22/SN:chr22/' | \
sed -e 's/SN:X/SN:chrX/' | sed -e 's/SN:Y/SN:chrY/' | \
sed -e 's/SN:MT/SN:chrM/' | samtools reheader - test.bam > test_chr.bam
If you want to do this for a bunch of bam files at once, use a loop. The variable $filename is your file without the extension (assuming there is no period except the one in ".bam").
for file in *.bam
do
filename=`echo $file | cut -d "." -f 1`
samtools view -H $file | \
sed -e 's/SN:1/SN:chr1/' | sed -e 's/SN:2/SN:chr2/' | \
sed -e 's/SN:3/SN:chr3/' | sed -e 's/SN:4/SN:chr4/' | \
sed -e 's/SN:5/SN:chr5/' | sed -e 's/SN:6/SN:chr6/' | \
sed -e 's/SN:7/SN:chr7/' | sed -e 's/SN:8/SN:chr8/' | \
sed -e 's/SN:9/SN:chr9/' | sed -e 's/SN:10/SN:chr10/' | \
sed -e 's/SN:11/SN:chr11/' | sed -e 's/SN:12/SN:chr12/' | \
sed -e 's/SN:13/SN:chr13/' | sed -e 's/SN:14/SN:chr14/' | \
sed -e 's/SN:15/SN:chr15/' | sed -e 's/SN:16/SN:chr16/' | \
sed -e 's/SN:17/SN:chr17/' | sed -e 's/SN:18/SN:chr18/' | \
sed -e 's/SN:19/SN:chr19/' | sed -e 's/SN:20/SN:chr20/' | \
sed -e 's/SN:21/SN:chr21/' | sed -e 's/SN:22/SN:chr22/' | \
sed -e 's/SN:X/SN:chrX/' | sed -e 's/SN:Y/SN:chrY/' | \
sed -e 's/SN:MT/SN:chrM/' | samtools reheader - $file > ${filename}_chr.bam
done
or just
sed -e 's/SN:\([0-9XY]*\)/SN:chr\1/' -e 's/SN:MT/SN:chrM/'
Thanks that is much more elegant. With an additional slight improvement my line is now:
for file in *.bam
do
filename=`echo $file | cut -d "." -f 1`
samtools view -H $file | sed -e 's/SN:\([0-9XY]\)/SN:chr\1/' -e 's/SN:MT/SN:chrM/' | samtools reheader - $file > ${filename}_chr.bam
done
Hi petervangalen and Pierre,
I also downloaded BAM files, where prefix "chr" is missing.
Is it necessary to add prefix "chr" only in header or also in each line of BAM/SAM ?
For eg:
samtools view -H HDG04N.exome.bam | sed -e 's/SN:\([0-9XY]*\)/SN:chr\1/' -e 's/SN:MT/SN:chrM/' | head -5
@SQ SN:chr1 LN:249250621
@SQ SN:chr2 LN:243199373
@SQ SN:chr3 LN:198022430
@SQ SN:chr4 LN:191154276
@SQ SN:chr5 LN:180915260
samtools view HDG04N.exome.bam | awk 'BEGIN {OFS="\t"} { print $1,$2,"chr"$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15 }' | head -4
HWI-ST1033:90:C0K0PACXX:8:2201:8091:30260 163 chr1 10004 8 100M = 10048 144 CCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCT CCCFFFFFHHHHHJJJJJJJJJJJJJJJJJJJJJJJJJJIJJJJJGHIIII@FHIIIGIIHGCCFDDFFAECCDB@C?ABDBDCA?BDDC?BDDDDDDDD NM:i:0 AS:i:100 XS:i:100 RG:Z:1
HWI-ST1033:90:C0K0PACXX:8:2201:8091:30260 83 chr1 10048 8 100M = 10004 -144 CTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAAC 8883DDB<<9DCA<8+BA<2<5DCA?=5DCA=>.CEB@;)HHHA=)IHGC@.IHCCB6IHDD?JJHGD:JIHFEAJJIHGEJJIGHGHHHGHDFFFFBBB NM:i:0 AS:i:100 XS:i:93 RG:Z:1
HWI-ST1033:90:C0K0PACXX:8:2302:17841:157944 163 chr1 10332 40 21M1I74M = 10365 135 CCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCCTAACCCCTAACCCTAACCCTAACCCTAACCCTA CCCFFFFFHHHGHJJJJJJJJJJJJJJJJJJJJJJJJIJJJJGGIJJIIJEGJCGGIJIIGHGEDDBDCDD@ABBAB<?BBB???BD@BCC?AABC NM:i:1 AS:i:88 XS:i:88 RG:Z:1
HWI-ST1033:90:C0K0PACXX:8:1304:9484:179936 163 chr1 10343 40 10M1I90M = 10358 117 CCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCCCTAACCCCTAACCCTAACCCTAACCCTAACACTAACCCTAACCCTAACCC CCCFFFFFHHHHHIIGJJJJIGJJIJIIJJIICHHFHFFGHIJIHCGHIICGGGGG;==ECEFDBDEEAAC@CCD2=<ACB(:>A3@8A?CC8<AACC@?< NM:i:2 AS:i:88 XS:i:88 RG:Z:1
Concatenate the output from both files as SAM and convert to BAM. Or simply converting it only in header is fine.
Thanks !
@Petervangalen if I had to use the above command for a vcf file then is the below command correct
| sed -e 's/SN:1/SN:chr1/' | sed -e 's/SN:2/SN:chr2/' | sed -e 's/SN:3/SN:chr3/' | sed -e 's/SN:4/SN:chr4/' | sed -e 's/SN:5/SN:chr5/' | sed -e 's/SN:6/SN:chr6/' | sed -e 's/SN:7/SN:chr7/' | sed -e 's/SN:8/SN:chr8/' | sed -e 's/SN:9/SN:chr9/' | sed -e 's/SN:10/SN:chr10/' | sed -e 's/SN:11/SN:chr11/' | sed -e 's/SN:12/SN:chr12/' | sed -e 's/SN:13/SN:chr13/' | sed -e 's/SN:14/SN:chr14/' | sed -e 's/SN:15/SN:chr15/' | sed -e 's/SN:16/SN:chr16/' | sed -e 's/SN:17/SN:chr17/' | sed -e 's/SN:18/SN:chr18/' | sed -e 's/SN:19/SN:chr19/' | sed -e 's/SN:20/SN:chr20/' | sed -e 's/SN:21/SN:chr21/' | sed -e 's/SN:22/SN:chr22/' | sed -e 's/SN:X/SN:chrX/' | sed -e 's/SN:Y/SN:chrY/' | sed -e 's/SN:MT/SN:chrM/' | input.vcf > output.vcf
You can use samtools view to dump your data with the header: http://samtools.sourceforge.net/samtools.shtml and replace the chromosomes with sed or awk.
(not tested but it could be something like this:)
samtools view -h file.bam |\
sed -e '/^@SQ/s/SN\:/SN\:chr/' -e '/^[^@]/s/\t/\tchr/2'|\
awk -F ' ' '$7=($7=="=" || $7=="*"?$7:sprintf("chr%s",$7))' |\
tr " " "\t"
You could also use PICARD ReplaceSamHeader.
if you need to work with samtools or the gatk, another hack is to create a 'mock' faidx index to the reference genome. See my blog.
@Pierre, is there a concern about sequences that may not be the same in the aligned BAM and in the new ref fasta she wants to set? I mean, perhaps, alignment has been made with a patched version or something else... in a word are we sure by doing this that a particular position is exactly the same in both references ?
quick note: not all sed versions can match a tab with t ... pretty annoying I agree ... in those case one should rewrite the sed line to awk with gsub
I know it works, but i would like to understand it a bit better, if possible. I tried the same without the awk and tr and it also works fine. the sed command add the 'chr' into the right place. What exactly does awk do afterwards?
the 7th column contains the name of the chromosome. You have to add the chr prefix if this value is different from "=" or "*"
ok. I get it. somehow my bam file has the chromosomes on the 3rd. column:
HWI-EAS225_0031_FC:2:1:19139:1546#0 99 2R...
HWI-EAS225_0031_FC:2:1:19139:1546#0 147 2R...
On the 7th column I have only [*|=]
My problem was that it added in my header on the 7th column also a 'chr'.
@Pierre This command works fine, but what if you want to save the changes so that you create a new .bam file with the new chr notations? I just putted " > newfile.bam" at the end (after the final " in the tr command) but that doesn't seem to work. Am I overlooking something?
there's a command 'replace header' for samtools. See the doc.
@Pierre I tried the code but something was not right. It really replaced '1' with "chr1". But next I failed to get the index file for the bam file. The error is "samtools index: file.bam is in a format that cannot be usefully indexed". I used samtools view -H to check @HD VN:1.3 SO:coordinate chr @SQ SN:chr1 LN:249250621 AS:NCBI37 M5:1b22b98cdeb4a9304cb5d48026a85128 UR:file:/net/1000g/mktrost/seqshop/gotcloud/gotcloud.ref/human.g1k.v37.fa chr
I guess the issue comes with the awk line of the code as it checks the 7th column; being either "=" or "*" and adds "chr" if doesn't match. Then the header lines are also added a "chr" on the 7th column. I don't know about the speed but modifying the awk and tr lines as below could work
awk -F '\t' 'BEGIN{OFS="\t";} { if ($1 !~ /^@/ && $7 != "=" && $7 != "*") {$7 = "chr"$7; print$0;} else print$0}'