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.