Inherited differences in gene copy number, known as copy number variation (CNV), have been implicated in some hereditary diseases but none of the previously discovered familial cancer genes has had CNV as the genetic change.
"This alteration is unlike anything we have ever seen before in families that tend to develop the same kind of cancers," says Michael Kelley, M.D., an associate professor at Duke University Medical Center and senior author of the study appearing in Nature Genetics. "We are not talking about a mutation in a single gene, but the duplication of an entire gene. This discovery is a classic example of where science answers one question but raises many, many more."
Chordoma is rare, striking only one in every million people. But it is a devastating diagnosis. People who have the disorder typically develop tumors at the base of the skull, in the pelvis, or along the spinal column. The growths are thought to arise from remnants of the notochord, an embryonic precursor to spinal column. There are few treatments and no cure for chordoma; most who have the disease usually die within 10 years.
Kelley, chief of hematology and oncology at the Durham Veterans Affairs Medical Center, has been studying chordoma for years after a collaborator at the National Cancer Institute, Dilys Parry, a co-author of the study, discovered a family with a history of the disease spanning several generations. They concluded that there had to be some sort of inherited genetic defect at work. Parry conducted clinical studies that eventually identified six additional families with multiple relatives with chordoma.
Initial work focused on possible defects on chromosome 7, but no defect was found that was shared by all of those affected. Researchers conducted linkage studies that revealed six new areas in the genome where potential mutations were likely. But it wasn't until they used a technique called array comparative genomic hybridization, a method that allowed them to see structural changes in the genome in exquisite detail, that they were able to pinpoint the source of the culprit. They identified it as the T (Brachyury) gene on chromosome 6.
"Brachyury is a transcription factor that helps regulate the development of the notochord and we know the gene is overly active in the tumor tissue in many people with chordoma," says Kelley, "so we were pretty sure we were on to something."
Investigators screened 65 individuals (21 with chordoma) in seven families with a history of the disease, specifically looking for any alterations in the T gene. They discovered that all the patients with chordoma in four of the seven families had a second copy of the T gene. The duplication did not appear among members of the three other families, nor did it appear in 100 healthy, normal controls.
Kelley says investigators do not understand what Brachyury does to cause chordoma. Brachyury expression was found in tissue from chordomas not only in patients who had inherited the duplication but also in those who did not have the duplication.
"It is likely that other genes are at work here, or that some other mechanism we do not yet understand is in play. Based on our research, however, we do feel that it may be worthwhile to screen for complex genomic rearragements when trying to find the cause of familial cancers. It may be a more productive route than traditional gene-mapping methods."
Xiaohong Yang of the National Cancer Institute wrote the first draft of the paper, and along with David Ng, also of the NCI, analyzed the data. Ng, Sufeng Li, Kelly and David Alcorta, all of Duke, performed the laboratory studies including genotyping, sequencing and breakpoint evaluation. Parry, Ng, Eamonn Sheridan of St. James Hospital in Leeds, UK, and Norbert Liebsch, from Massachusetts General Hospital, identified and evaluated the chordoma families. Yang, Ng, Kelley, Parry and Alisa Goldstein planned the work and interpreted the results.
The study was funded by the U.S. Department of Veterans Affairs, the National Cancer Institute and the Chordoma Foundation.
Michelle Gailiun | EurekAlert!
Rutgers scientists discover 'Legos of life'
23.01.2018 | Rutgers University
Researchers identify a protein that keeps metastatic breast cancer cells dormant
23.01.2018 | Institute for Research in Biomedicine (IRB Barcelona)
Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.
Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
23.01.2018 | Life Sciences
23.01.2018 | Earth Sciences
23.01.2018 | Physics and Astronomy