Great! We did think of using Nextera exome kit but have no experience on that before. Can you let me know how the result turns out when it is out? That would be great help to decide how to proceed. Many thanks.
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Originally posted by henry.wood View PostWe are currently awaiting the results of FFPE exomes. We used the illumina nextera exome kits. They worked with <100ng DNA from FFPE samples. The libraries looked fine, but we won't know how the data turns out for a week or so.
I know people have used sureselect kits with FFPE in the past, but I think they need higher amounts of template. I don't know about truseq.
I would like to reiterate HoneyBee's question. Were you successful using the Nextera DNA prep/exome enrichment with FFPE samples? How degraded was the DNA prior library prep and what was the final library size distribution?
Thanks.
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I'd forgotten I said I'd report back. Oops. So the libraries worked OK. The DNA was reasonably good quality for FFPE, so degraded a bit, but still possible to do 500bp PCRs. It was proper surgical material pulled out of the archives though, not just quickly fixed and then immediately extracted, so a reasonable test. The libraries all had a size range between 200bp and 1000bp with normalish distribution. We did some fresh libraries at the same time and the FFPE ones looked the same.
When we did the sequencing, we were a little disappointed with the percentage on target, around 50-60, but this was the same for fixed and fresh, so just a product of the kit, rather than the samples. For what we want to do, this makes the sequencing a bit pricey, as we can restrict ourselves to only the best samples and use sureselect, so we then don't need to sequence as much to get the same depth. If sequencing cost isn't such an issue, but you only have a few samples which absolutely must get done, then it would be fine.
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wow~ Good news that Nextera exome works on FFPE samples.
May I know the fragment size of your FFPE samples? We are now working on some FFPE samples with fragment size < 100 bp... majority at ~50 bp.. How can you get FFPE DNA of good quality? We never get DNA larger than 200 bp..
Btw, just heard from Illumina that they are going to discontinue Nextera exome kit. Are you seeking alternatives right now?
Originally posted by henry.wood View PostI'd forgotten I said I'd report back. Oops. So the libraries worked OK. The DNA was reasonably good quality for FFPE, so degraded a bit, but still possible to do 500bp PCRs. It was proper surgical material pulled out of the archives though, not just quickly fixed and then immediately extracted, so a reasonable test. The libraries all had a size range between 200bp and 1000bp with normalish distribution. We did some fresh libraries at the same time and the FFPE ones looked the same.
When we did the sequencing, we were a little disappointed with the percentage on target, around 50-60, but this was the same for fixed and fresh, so just a product of the kit, rather than the samples. For what we want to do, this makes the sequencing a bit pricey, as we can restrict ourselves to only the best samples and use sureselect, so we then don't need to sequence as much to get the same depth. If sequencing cost isn't such an issue, but you only have a few samples which absolutely must get done, then it would be fine.Last edited by HoneyBee; 03-05-2013, 12:49 AM.
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I guess I'm a bit luckier than you with my sample sizes. Most of the FFPE samples have a fairly wide size range. The peak is around 100-200bp, but the tail often goes as high as 700bp. We prepare the DNA using the QIAamp DNA micro kit. I suspect that the kit doesn't matter too much, but that the damage gets done when the tissue is fixed. There are a wide range of fixing protocols, and some will damage the DNA more than others. We have no control over this, as we get our samples from the archives. We have plenty that don't work, but we don't attempt to sequence them.
I hadn't heard that the nextera exome kits were stopping. We only used them as a trial. We'll probably go with sure select in future, since the percentage of reads on target is better. I've heard there are some FFPE tweaks you can do with their methods, but I haven't tried them yet.
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Originally posted by HoneyBee View PostBtw, just heard from Illumina that they are going to discontinue Nextera exome kit. Are you seeking alternatives right now?
One difference is that the standard kit only covers 37Mbp of CDS only. They also have a Nextera Rapid Capture Expanded Exome Kit. I can't seem to dig up product specs for this one but I would guess that it expands coverage to the UTRs and flanking regions like the current TruSeq and Nextera Exome kits (target sizes of 62Mbp).
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