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Old 06-23-2009, 05:00 AM   #1
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Default PubMed: VarScan: Variant detection in massively parallel sequencing of individual and

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Related Articles VarScan: Variant detection in massively parallel sequencing of individual and pooled samples.

Bioinformatics. 2009 Jun 19;

Authors: Koboldt DC, Chen K, Wylie T, Larson DE, McLellan MD, Mardis ER, Weinstock GM, Wilson RK, Ding L

SUMMARY: Massively parallel sequencing technologies hold incredible promise for the study of DNA sequence variation, particularly the identification of variants affecting human disease. The unprece-dented throughput and relatively short read lengths of Roche/454, Illumina/Solexa, and other platforms have spurred development of a new generation of sequence alignment algorithms. Yet detection of sequence variants based on short read alignments remains chal-lenging, and most currently available tools are limited to a single platform or aligner type. We present VarScan, an open source tool for variant detection that is compatible with several short read align-ers. We demonstrate VarScan's ability to detect SNPs and indels with high sensitivity and specificity, in both Roche/454 sequencing of individuals and deep Illumina/Solexa sequencing of pooled samples. Availability and Implementation: Source code and documentation freely available at http://genome.wustl.edu/tools/cancer-genomics, implemented as a Perl package and supported on Linux/UNIX, MS Windows, and Mac OSX. CONTACT: [email protected] SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

PMID: 19542151 [PubMed - as supplied by publisher]



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Old 09-23-2009, 12:53 PM   #2
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Hello,
The program looked very useful from the description in the paper. I tried installing in Mac and Linux but it gave me errors (needed Math::Pari). I googled it and found some information but have not yet been able to solve the issue. Any tips?

Thank you!
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Old 10-21-2009, 04:39 PM   #3
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http://search.cpan.org/~ilyaz/Math-P...010801/Pari.pm ,install it。
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Old 10-21-2009, 04:44 PM   #4
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Thank you!
Shortly after I posted, I figure it out. The program worked fine. In fact, when I used ssaha2+samtools pileup or BLAT+Varscan, I obtained similar results in the number of SNPs that were known.
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Old 12-01-2009, 06:19 AM   #5
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I made alignments with bowtie and when i run varscan iam getting the error as alignment format not recognised, can some bdy help me ...

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Old 04-29-2010, 10:49 PM   #6
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Hi,

I'm trying to use Varscan to call indels.
I started from a pileup file made with Samtools, after alignment with Bowtie. When I used Varscan to call SNPS, it worked fine, but now it doesn't seem to find any indels. Should I change something in the parameters? Or do I need to change parameters during the alignment with Bowtie (I used all default parameters).
I really don't understand why it can call SNPs, but not indels.
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Old 04-29-2010, 11:14 PM   #7
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Quote:
Originally Posted by Lien View Post
Hi,

I'm trying to use Varscan to call indels.
I started from a pileup file made with Samtools, after alignment with Bowtie. When I used Varscan to call SNPS, it worked fine, but now it doesn't seem to find any indels. Should I change something in the parameters? Or do I need to change parameters during the alignment with Bowtie (I used all default parameters).
I really don't understand why it can call SNPs, but not indels.
Bowtie does not support indels. Try BFAST or BWA, which support indels.
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Old 06-17-2011, 08:16 AM   #8
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Default VarScan indels problem

Can we use topHat for the similar problem?
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Old 07-21-2011, 07:41 AM   #9
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Now I am trying to use bfast with BWA to map our reads. for bfast+bwa workflow, there are total five steps:
1. The first step is to create a reference genome from an input FASTA file that contains all
the sequence to which we wish to align. (bfast fasta2brg)
2. The second step is to create indexes of the reference genome, which was created in the
first step. (bfast index)
3. The third step is to find candidate alignment locations (CALs) for each read. (bfast match)
4. The fourth step is to fully align each CAL for each read. (bfast localalign)
5. The fifth and final step is to prioritize the final alignments. (bfast postprocess)

Now I got the problem in step 4. Aborted error came out. Based on my search, I guess our origninal paired reads is too large for this software. Now I try to break the one end reads into several parts, then repeat the first three steps in bfast.
Any Guidance??
Best,
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Old 07-21-2011, 07:42 AM   #10
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What is the error message in step 4 (copy and paste please). Can you isolate it to just a few reads for ease of debugging?
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Old 08-07-2011, 11:41 PM   #11
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Hi,
Probably a very stupid newbie question, but a have a problem with the pileup2indel option of Varscan. When I look in Samtools tviewer I find several Indels with a varfreq of 100%, however Varscan gives these variants a Varfreq of 50%. The problem seems to be that varscan takes the coverage of the base before the indel as reads1, thereby approximately doubling the total number of reads on the indel position. This results in varfreqs of about half the real variant frequency.....What am I doing wrong???
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