Individuals with mutations in BRCA1 and BRCA2 genes have a significantly higher risk of developing breast and ovarian cancers. Families at risk have been seeking genetic testing and counseling based on their mutation carrier status, but the standard method of direct sequencing is labor-intensive, costly, and it only targets a part of the BRCA1 and BRCA2 genes.
A group of Canadian scientists has developed a new sequencing approach to provide a more effective method of BRCA1/2 mutational analysis. Their work is published in the September issue of The Journal of Molecular Diagnostics.
"A comprehensive understanding of BRCA1/2 genotypes and the associated tumor phenotypes is needed to establish targeted therapies," notes lead investigator Hilmi Ozcelik, PhD, of the Fred A. Litwin Centre for Cancer Genetics, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada. "Recent studies have suggested that certain chemical inhibitors are effective for the treatment of breast cancer in patients with BRCA1/2 mutations. Therefore, availability of new, affordable, and comprehensive technologies to screen for these mutations will be critical to identify patient-candidates for targeted therapies."
The investigators used a technique called long range PCR to generate amplified BRCA1/2 fragments, known as amplicons, from the DNA of 12 familial breast cancer patients. The amplicons were screened using deep sequencing, also known as Next Generation Sequencing (NGS), which allows for the simultaneous screening of millions of DNA molecules, thereby dramatically increasing speed and throughput. While conventional screening methods target only the exons of BRCA1/2, deep sequencing can screen the entire genomic region, including introns and untranslated regions. The specimens had been previously analyzed using conventional methods, allowing for a comparison of results.
In addition to identifying one genetic variant that was missed due to human error, the new method successfully identified all of the expected BRCA1/2 variants. They identified both exonic and exon/intron boundary variants. The test was done at a very low cost, and with a turnaround time of 12 days. "One of the key advantages of workflow of long-range PCR is the ability to visually detect large genomic duplications, deletions, and insertions," notes Dr. Ozcelik. "When combined with next generation sequencing, long range PCR can be a powerful tool in the detection of BRCA variants in the clinical setting. Our method confirmed the presence of variants with very high accuracy, and without false-positive results."
Long-range PCR and next generation sequencing identified a wide range of intronic BRCA1/2 variants, both commonly occurring and rare, that individually or in combination may impact BRCA1/2 function. Dr. Ozcelik notes that despite a small sample size, the data shows great variability in the number, type, and frequency of variants that can be identified from familial breast cancer patients.
"Our challenge now is to establish analytical methods that systematically investigate this more comprehensive data in order to provide better risk information for clinical management of the disease," says Dr. Ozcelik. "Given the extensive level of genetic information acquired from each patient, profiles can be constructed in breast cancer patients compared to population controls to produce a more effective means of generating BRCA1/2-associated risk to the individuals and their families.
David Sampson | EurekAlert!
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
Migrating Cells: Folds in the cell membrane supply material for necessary blebs
23.11.2017 | Westfälische Wilhelms-Universität Münster
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
23.11.2017 | Information Technology
23.11.2017 | Physics and Astronomy
23.11.2017 | Life Sciences