View Single Post
Old 10-24-2011, 06:39 AM   #16
Senior Member
Location: USA, Midwest

Join Date: May 2008
Posts: 1,155

Originally Posted by skruglyak View Post
We are planning a minor release of CASAVA in October that is primarily intended to handle an improvement to the number of supported index sequences. In the same release, we plan to change the default behavior and omit reads that do not pass filter from the FASTQ files. In general, we do not recommend the use of non-PF reads. Users that want to retain the non-PF reads will be able to do so by adding the following parameter to the


A read is classified as non-PF when more than one cycle in the first 25 cycles has a poor ratio (<0.6) of the brightest intensity to the sum of the brightest and second brightest.
Our variant calling software ignores non-PF reads, but there are many alternate methods that use all data, disregarding the non-PF flag. The inclusion of non-PF reads increases time to align, increases the data footprint, increases the measured error rate, and can lead to variant calling errors. As a result we have decided to exclude such reads as the default behavior. As a consequence of being excluded from the FASTQ files, the reads will also be excluded from all downstream processing and output including BAM files archival and standard.

Please let me know if you have questions or concerns.

Thank you,

I really appreciate that Illumina has been so responsive to customer feedback with regard to refinement of the CASAVA pipeline and I really hate to keep coming up with more things to tweak/change, but...

I just ran my first data set through the new 1.8.2 pipeline and truly appreciate the PF only default and --fastq-cluster-count 0 options, however I noted what I consider a bug in some of the summary files produced by CASAVA. Some summary files (e.g. Flowcell_demux_summary.xml) report the number of PF clusters/bases for for both raw and PF counts. Other files (e.g. BustardSummary.xml) appear to correctly report raw and PF.

Thanks again.
kmcarr is offline   Reply With Quote