[Update: 2021-01-10: Thank you for your interest in our book club. We are currently closed to new members, but you can watch and subscribe to our meetings on the Genomics in the Cloud Book Club channel on YouTube.]
Introducing the Genomics in the CloudBook Club, an online discussion group. Our 30+ members across 10 time zones are covering one chapter each week, and we expect to complete the book in March 2021.
Taking a page from the R for Data Science Online Learning Community, we created a Slack account for discussions and a Zoom account for meetings. Last week, we had lively online conversations about reference genome diversity, workflow language selection, personal whole genome sequencing, reproducibility tips, and more.
After each meeting, we post the video to this GITC Book Club channel on YouTube so you can follow us anytime. Our member’s tweets are also available here. Thank you for tuning in!
One of the limitations of the family trio work was that the bioinformatics pipelines were different between our samples and our kids’ samples. To fix this limitation, I had to “reconstitute” the original FASTQ files from the BAM file provided by Illumina and then re-run all our data through the same pipeline. (Note: To my knowledge, UYG no longer provides BAM files as part of this program.)
You can create FASTQ files from your BAM file by using Picard, a set of Java-based command line tools for manipulating high-throughput sequencing (HTS) data in formats such as SAM/BAM/CRAM and VCF.
For reasons that escape me now, I first ran Picard using an AWS t1.micro instance.
After 3 attempts–watching Picard fail after running for 3 days each time–and creating thousands of temp files in the process, I learned the hard way that Picard requires more than 613 MBytes of memory. This time, I used a c4.2xlarge instance (4 cores, 16 GBytes of memory), which worked. It appears that 16 GBytes is about the minimum amount of memory to get the job done.
Step 1. Is your BAM file sorted?
Before creating FASTQ files, make sure your BAM file is sorted so that your genome coordinates are in order. One of the ways to do this is with samtools, a suite of programs for interacting with HTS data. Here are the commands I used to install it. You can check whether or not your BAM file is sorted by using this command:
samtools stats YourFile.bam | grep "is sorted:"
# "is sorted: 1" = Yes, your BAM file is sorted.
# "is sorted: 0" = No, your BAM file is not sorted.
If your BAM file requires sorting, use this command (or something close to it):
# Type "samtools sort --help" for a description of this command
samtools sort -n -@ 2 -m 2560M InputFile.bam -o ./OutputFile.sorted.bam
# Check for existence of Read Groups (@RG)
samtools view -H InputFile.bam | grep '^@RG'
Step 2. Run Picard
Get Java and the picard.jar file. Run this command, but keep in mind that the options below are for a BAM file created on an Illumina HiSeq sequencer:
Using the c4.2xlarge instance, I ran Picard in 3 hours to create the FASTQ files shown below. In addition, creating compressed (gzip) versions of the files required another 8.5 hours of compute time. With an on-demand price of about $0.40 per hour, creating compressed FASTQ files cost approximately $4.60 USD on AWS.
I launched my first cloud server literally while in the clouds in May 2014. Cloud computing has changed so much, it’s unbelievable. Back then, I had to patch the Linux kernel by hand so that the ftp server would work on AWS. Today, uploading your genome using Amazon’s command line interface (CLI) to an AWS S3 storage bucket is relatively easy. Understandably, Amazon makes it challenging (but doable) to make your storage publicly available. I used the Apache Web Server and s3fs to share this information.
s3fs allows allows you to mount an S3 bucket via FUSE. s3fs preserves the native object format for files, allowing use of other tools like AWS CLI. Again, your commands may vary depending on your flavor of Linux. Here are the commands I used to install s3fs.
Hosted by the Mind First Foundation, this conference enabled participants in the Personal Genome Project to hear first-hand how their health data could be used in research, especially mental health research. The second day of the conference, the “PGPalooza,” let PGP participants directly interact with researchers to select projects of interest and have their questions answered immediately.
James Tao graciously edited this 25-minute video of my talk about family trio sequencing and autism:
Also, special thanks to Alex Hoekstra, co-founder of Mind First, for the invitation to this event.
In this blog post, I look at whole genome sequence platforms for storage and discuss what might happen to “genomical” amounts of data.
When I uploaded my whole genome sequence in September 2014 (about 10 months ago), few options existed for sharing personal genomic data. The usual suspects (Dropbox, Evernote and Figshare) were prohibitively expensive for large amounts of data. I knew about DNAnexus, but I saw it as a platform for researchers, not consumers. Well, times have changed. Fast.
A Battle of Platforms?
In addition to my original “roll your own” approach, DNAnexus and Google Genomics have emerged as major players for end-to-end genomics workflow. In the table below, you can see that storage costs for AWS S3, DNAnexus and Google Genomics are roughly the same. Everyone provides free uploads (we want your data!), but the cost for transferring data out of the systemvaries. Google Genomics does not charge for this, but instead charges for API access. For my current AWS storage, I pay about $4 per month to store my genome.
Astronomical becomes Genomical: A Perspective on Storage
In this recent article about big data and genomics, the authors compare the field of genomics with three other Big Data applications: astronomy, YouTube and Twitter. In common with genomics, these domains: 1) generate large amounts of data, and 2) share similar data life cycles. The authors examine four areas–acquisition, storage, distribution, analysis–and conclude that genomics is “on par with or the most demanding” of these disciplines/applications. My previous experience in medical imaging (a field that arguably tackled the prior generation of “big data” issues) leads me to believe that genomics will come to epitomize Big Data to many more people before long.
If you look carefully at the projections in the figure above, we may run out of genomes to sequence (really?), which brings us back to storage. Where will we store all of this sequence data, especially as genomic medicine continues its inexorable move to the clinic?
Delete Nothing and Carry on
If the field of medical imaging is an indicator, deleting anything after it has been archived is the exception rather than the rule. The main reason for this is medicolegal — hospitals avoid the liability of not being able to recall an exam later by keeping everything. Although the incidence of requiring access to images after diagnosis is low, the consequence of not having access to the original diagnostic image is high. A former colleague suggested that about 5% of their medical archive customers use lifecycle management features to delete imaging exams. In medical imaging, customers more commonly use lifecycle management features to migrate images to less expensive storage devices over time. So, in genomics, you might migrate your sequence data stored on Amazon from solid state storage (most expensive) to S3 to Glacier (least expensive). But my best guess: we’ll delete nothing and carry on.
The project began with a crowdsourced effort to raise $1,750 to sequence our daughter’s genome, and took slightly more than two months to complete. After working with AllSeq and HudsonAlpha to obtain WGS data, we used VarSeq from Golden Helix to search for unique variants, as well as browse whole genome sequence data. After filtering our variant call data to focus on high quality exome variants, we examined 52 potentially damaging de novo and compound heterozygous changes suggested by VarSeq’s family trio analysis. Although this first approach did not yield clues specific to autism, it did suggest a number of secondary findings that are not addressed here. The second approach was to start with genes having known associations with autism and then look for them in our daughter’s DNA. Several curated databases have between 200 and 700 genes, but again, none produced meaningful results. The third method was to look at known “hot spots” in autism genetics, such as variants in the NRXN1 gene, as well as known structural variation on chromosome 16. Changes to NRXN1 and so-called “16p” changes are discussed below.
NRXN1 – Deletions in NRXN1 are associated with a wide spectrum of developmental disorders, including autism. Our daughter has a 10bp exonic deletion (-GT repeat) followed by what appears to be a 9bp compound heterozygous deletion in NRXN1. Both deletions are partially present in both parents and overlap; the deletions appear to have been accumulatively inherited. Due to the high number of sequence repeats, copy number variation (CNV) should clarify the significance of this finding.
16p deletions – Deletions and duplications in this 593-kilobase section of chromosome 16 are widely associated with developmental issues, including autism. Our daughter appears to have dozens of deletions in this region, some inherited and some not. However, since the variants in our daughter’s DNA were called using a different software pipeline, it is difficult to draw meaningful conclusions (see “Limitations,” below). For example, some variants in our daughter’s DNA were shown to map to multiple places on the genome, suggesting either large copy number variation or genomic regions that were difficult to map. Copy number variation (CNV) analysis will also elucidate this region. Once resequenced, this region has the potential to provide genetic clues to our daughter’s condition.
My wife and I received our WGS data in March 2014. Our samples were sequenced at 30x coverage using Illumina’s HiSeq platform and then aligned and called with Illumina’s pipeline, Isaac. Our daughter’s DNA was sequenced in May 2015 at 30x coverage, but on Illumina’s newest platform, the Illumina HiSeq X Ten. The difference is that our daughter’s DNA was aligned using BWA, followed by variant calling with GATK “best practice” workflow. To accurately compare genomes in family trio analysis, all samples must be processed using the same software pipeline. Otherwise, variants may be aligned and called differently. My wife and I must go back to the (almost) original FASTQ data and start over. Although Illumina did not provide these files with our results, Mike Lin from DNAnexus explains how to extract FASTQ files from Illumina data in this great blog series. Hint: it involves a utility called Picard (no relation). Until we resequence our WGS data using the same bioinformatics pipeline, all results should be considered preliminary.
This project demonstrated that personal genomics is very real, and has the potential to answer complex medical questions. Today, answering those questions using whole genome data and family trio analysis requires a combination of genetic, bioinformatic and domain knowledge to reach meaningful conclusions. Validating those conclusions remains challenging, from rare diseases to complex conditions such as autism. Currently, personal genomics has a similar feel to “homebrew” computer clubs from the late ’70s–the community is still very small, collegial, and willing to share “tips and tricks” to advance the field.
Although we encountered some “dark alleys” during the analysis, our preliminary results suggest that family trio sequencing can indeed provide genetic clues to autism. We will continue to refine the analysis by resequencing the data with the same pipeline, which should resolve questions in the 16p region, as well as the potential deletion in NRXN1. Further, CNV analysis should answer structural variation questions that are also known to be associated with autism spectrum conditions.
I would like to thank our backers and the team at experiment.com, as well as Gabe Rudy from Golden Helix. Gabe was very generous with his time, knowledge and insight. Finally, I would like to thank my wife, Kimberly, for her patience and fortitude.
This entry was cross-posted from DNAdigest on April 22, 2015.
Amazingly, the cost of whole genome sequencing is now 100,000 times less expensive than it was a dozen years ago. If the Tesla Model S followed this trajectory, you could buy one today for less than $1 USD. This super logarithmic decline puts genomics on par with desktop publishing or 3D printing—it has become something that you can affordably do yourself.
My wife, Kimberly, and I were excited about the prospect of having our genomes sequenced. Our daughter has autism, and like many parents of special needs children, we were eager to explore the underlying causes of her condition. We “got genomed” last year by enrolling in Illumina’s Understand Your Genome program. We received our whole genome sequencing (WGS) data, as well as limited predisposition and carrier screening for a number of Mendelian traits. As many DNAdigest readers know, the cost of WGS continues to drop in price, almost to the $1,000 genome that Illumina announced last year. Kimberly and I were intrigued to learn that we were both carriers of some rare genetic variants. Could our genetic idiosyncrasies be contributing to our daughter’s autism?
After being sequenced, I followed the lead of DNAdigest contributor Manuel Corpas and posted my whole genome sequence online. I decided to publish my genome without restrictions in an attempt to lead by example. In the future, platforms like Repositive will make it easier for consumers to share genomic information and maintain privacy.
Kimberly and I recently launched a project on experiment.com to crowd fund the whole genome sequencing of our adult-aged daughter. In this project, we will look for genetic clues to her autism using family trio sequencing. Family trio sequencing is a powerful technique that can explain genetic conditions by looking at differences in DNA between Mom, Dad and an affected child.
We were thrilled when the sequencing project was funded the first day. In the process, we received feedback from other parents who wanted to learn more about the technique, so we added a stretch goal to cover publishing costs in an open access journal. The research paper will document our findings, as well as explain how family trio sequencing can be used to search for answers to health conditions and rare diseases.
Information sharing can indeed be very personal, but we find the possibility of catalyzing new areas of health research compelling. With this project, we hope to find clues that will contribute, if only in a small way, to a growing body of genomics research that supports a broader explanation of autism.