Scientific Collaborators in New York and Jerusalem Uncover New Mutation Underlying Rare Sensory Disease

The study described below was published in the April 2012 edition of the Annals of Neurology, the journal for the American Neurological Association and the Child Neurological Society.

At a time when many people are asking when DNA sequence information will have a real application in healthcare, a nonprofit organization based in Brooklyn, New York, is proving that linkage mapping and exome sequencing are already making a major difference in people’s lives.

Bonei Olam is charged with helping families with genetic or undiagnosed diseases, many of them dealing with infertility challenges, to conceive healthy babies using tools such as pre-implantation genetic diagnosis. In 2008, Bonei Olam opened its Center for Rare Jewish Genetic Disorders to find the underlying molecular causes of some of these conditions. They responded to hundreds of families who had been unable to find a diagnosis through traditional medical routes, and established key collaborations with universities, including Hadassah Medical Center in Israel, to help perform the studies. Over the years, the center has funded SNP arrays, Sanger sequencing, variant validation, and the sequencing of more than 100 exomes for family after family.

It was through one of those studies that collaborators from Hadassah Medical Center, New York University, and Bonei Olam discovered a novel mutation that leads to a previously uncharacterized disease linked to hereditary sensory autonomic neuropathy, a group of disorders with the common theme of loss of function in peripheral sensory nerves. This new version is far more severe than its familial dysautonomia cousin and is caused by a mutation in the DST gene, which destabilizes the Dystonin protein. The study, called “Hereditary sensory autonomic neuropathy caused by a mutation in dystonin” was published by Dr. Simon Edvardson, Prof. Orly Elpeleg, and the rest of their team in the Department of Genetic and Metabolic Diseases at Hadassah in the April 2012 issue of Annals of Neurology.

Chaim Jalas, Director of Genetic Resources and Services at the Center for Rare Jewish Genetic Disorders and a co-author on the paper, says that this particular project began when two related families approached Bonei Olam, each having lost at least one child to this uncharacterized disease. The disorder was lethal: all of the affected children, three in total, died by the age of 2.

The team started off with SNP arrays to perform linkage analysis in both families, and later performed exome sequencing on one of the affected children to find the causative mutation. Much of the clinical and functional work in the eight-month project — including identifying the mutated gene and studying its effect in cell lines — was led by Prof. Orly Elpeleg at Hadassah Medical Center in Jerusalem.

Since Bonei Olam doesn’t have an in-house bioinformatics team, Jalas relies for interpretation on various software tools as well as the cloud-based storage and analysis platform from DNAnexus. For this project, he uploaded the raw sequence reads to DNAnexus and ran the Exome analysis tool followed by the Variant analysis tool, which located the mutation — the DST variant that results in an unstable transcript in Dystonin, a protein used in the cytoskeleton. “What DNAnexus does for us is all the bioinformatics, starting from uploading raw reads to performing the alignment, the variant calling, the annotation, and graphical display of the reads on the reference genome,” Jalas says. In the past, the DNAnexus Variant analysis tool has been able to find a variant that other software packages have missed, he says — but he’s most confident when two different software packages call the same variant so it’s more likely to be real.

Once DNAnexus returned the answer, Jalas shared the data with his collaborators, who could log in with their own accounts to review the information. Finally, the research team confirmed the mutation by Sanger sequencing.

Since Bonei Olam isn’t your typical research institute, the real triumph was not the research finding or the publication of this mutation; it’s that “one of the two families is currently pregnant with a healthy baby,” Jalas says.

Ultimately, the success of these studies may prompt Bonei Olam to move toward whole genome sequencing. “I think at some point we will do whole genomes,” Jalas says. “We’re looking into a pilot study of families for whom exome sequencing did not find a causative genetic mutation where we know for sure it’s a genetic condition.”

Paper information:
Hereditary sensory autonomic neuropathy caused by a mutation in dystonin
Simon Edvardson, MD; Yuval Cinnamon, PhD; Avraham Shaag, PhD; Orly Elpeleg, MD, from Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center
Chaim Jalas, from Bonei Olam, Center for Rare Jewish Genetic Disorders
Channa Maayan, MD, from Department of Pediatrics, Hadassah, Hebrew University Medical Center
Felicia B. Axelrod, MD, from Department of Pediatrics, New York University School of Medicine
DOI: 10.1002/ana.23524
http://onlinelibrary.wiley.com/doi/10.1002/ana.23524/abstract

Seeing The Trees In The Forest

One of the biggest challenges associated with the identification of genomic variation, is finding those that have a real and measurable impact and help explain, for example, a disease or drug response under investigation. Weeding through more than 5 million variants associated with the human genome is a huge effort that requires significant computational infrastructure and staff time to manually validate and correlate the identified biological findings associated with the data obtained. To expedite this process and free up more time for focusing on relevant data, these data must be narrowed down to a manageable size – ideally less than a few hundred variants.

We have just released a number of new features that will help solve this challenge by providing:

  1. Smart variation results filtering
  2. Linkouts to public and commercial data sources with gene to disease information

With this new functionality, you can – with a few simple queries – home in on the most relevant variants, whether they are associated with a specific gene, a coding region, a specific chromosome, or annotations that fulfill a specific set of characteristics. The result is quicker insight into affected processes that directly translates into faster hypothesis generation and decision making.

More Specifically…

To help you rapidly drill down on biologically interesting and relevant results, we have created a flexible query tool for filtering your variation analysis results within the DNAnexus Genome Browser. With just a few clicks, you can apply any number of filters to a results table, yielding a set of variant calls that allow easy navigation through the browser and further investigation.

In this release, we have added 13 distinct filters, including chromosome, variant type, gene/transcript name, zygosity, location relative to gene/transcript, among others. These filters are currently available for the DNAnexus Nucleotide-Level Variation (see screenshot below) and Population Allele Frequency analyses results. We are also working towards making them available for any data type, including RNA-seq and ChIP-seq data. All of the filtered results can be exported out of DNAnexus for further analyses in other tools, such as Excel or statistical tools.

Understanding And Validating Variant To Gene To Disease Results

To help you understand a prioritized list of variants as well as the genes and processes impacted as a result of these variants, we have included the ability to link out to other third party data sources, both public and commercial data sources that contain relevant gene-to-disease knowledge, allowing you to study how identified variations in DNA affect the response to diseases, bacteria, viruses, toxins and chemicals, including drugs and other therapies.

It’s All About The Data

DNAnexus specializes in addressing the data storage, management and analysis challenges inherent in next-generation sequencing. We believe that by leveraging the cloud, being data-source/platform agnostic we can provide the best possible support for anyone using these data in their work. We also believe that your input regarding what data is accessible through DNAnexus is critical and because our platform is flexible we can easily integrate with many of the data sources you would like to access or need for your research.

DNAnexus currently supports direct linkouts to 12 public and commercial data sources including: AmiGo, BioBase, Cosmic, dbSNP, Entrez Gene, GeneCards®, IPA®, KEGG, NextBio, OMIM, PharmGKB, Pubmed. For commercial data sources, we can provide integrated access for users who have licenses to access these data.

Please let us know if there are specific data that you would like to access via DNAnexus by emailing us at support@dnanexus.com.

Take Me To The Data

To access these data sources we have added the new Gene Info pages (see the BRCA1 Gene Info page as an example below), which provide a gene overview and a list of all the data sources accessible. Gene Info pages are meant to give you a preview of the gene, with linkouts to additional information.

Gene Info pages are accessible through hyperlinked gene names within the DNAnexus Genome Browser and analysis results tables, as shown here.

We now support 22 reference genomes, the latest additions include Staphylococcus genome S. epidermidis ATCC 12228 and the Macaque genome M. mulatta.

Tell Us What You Think

Much of the new functionality that makes its way into the DNAnexus platform is the result of requests by our many active users. We cannot emphasize enough how much we value user feedback; it is a critical component of our product development and feature prioritization process.

To simplify the process of providing feedback, we have added feedback links to both the filterable results tables and the Gene Info pages. You are also welcome to email us at support@dnanexus.com with any feature requests or questions you may have. We look forward to hearing from you and keeping you posted on the many new features we are working on and will be releasing in the coming months.