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Archive - Oct 24, 2013

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Gene-Diet Interaction Study Identifies Significant Variants Associated with Diet-Related Risk of Colorectal Cancer

A newly discovered potential gene-diet interaction for colorectal cancer was reported today (Thursday, October 24) at the American Society of Human Genetics(ASHG) 2013 meeting in Boston. The interaction may shed light on the statistically significant increased risk of colorectal cancer that is associated with consumption of red and processed meat, the researchers said. “If replicated, our findings have a relevant public health significance because diet is a modifiable risk factor for colorectal cancer,” said Jane Figueiredo, Ph.D., Assistant Professor of Preventive Medicine at the University of Southern California Keck School of Medicine, who presented the study this morning at the ASHG meeting. “It is conceivable that selected individuals at higher risk of colorectal cancer based on genomic profiling could be targeted for screening, diet modification and other prevention strategies,” added Dr. Figueiredo, one of the scientists collaborating in the international NIH-funded Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). The scientists also determined that the lower colorectal cancer risk associated with vegetable, fruit, and fiber intake also was linked to genetic variants. The possibility that genetic variants may modify an individual’s risk for disease based on diet has not been thoroughly investigated but represents an important new insight into disease development, said Ulrike Peters, Ph.D., M.P.H, who headed the study and is a Member of the Fred Hutchinson Cancer Research Center’s Public Health Sciences Division in Seattle, Washington.

Scientists Identify First Gene for Most Common Form of Mitral Valve Prolapse

Research on the DNA of a large multi-generational family has provided a genetic clue that enabled scientists to pinpoint a gene that plays a role in mitral valve prolapse (MVP), a common cardiac disease that is the leading cause of heart valve surgery, according to a study presented today (Thursday, October 24) at the American Society of Human Genetics (ASHG) 2013 meeting in Boston. MVP affects 2.5% of the population and typically presents symptoms in adulthood, often leading to heart failure. 15% of the patients inherit the disease, but the remaining 85% of MVP incidence is sporadic. The scientists who located the gene, named DCSH1 (from the dachsous1 gene in Drosophila), also determined how mutations in this gene disrupt the normal embryonic development of the mitral valve, one of the valves that controls blood flow in the heart. “This work provides insights into the pathways regulating valve growth and development,” said Susan Slaugenhaupt, Ph.D., Professor of Neurology in the Center for Human Genetic Research at Massachusetts General Hospital (MGH) and Harvard Medical School and one of the lead scientists in the collaborative group that conducted the research. “The results implicate a previously unrecognized paradigm in the development of long-term structural integrity in the mitral valve,” said Ronen Y. Durst, M.D., former member of Dr. Slaugenhaupt’s lab and now a senior cardiologist at Hebrew University and Hadassah Medical Center in Jerusalem. Dr. Durst presented the study this afternoon at ASHG 2013. The researchers’ first step was to link MVP to a region on human chromosome 11 in the DNA of the group of relatives with the heart disorder. By sequencing that DNA region in family members, the scientists were able to link mutations in DCSH1 to MVP.

BROCA Panel Provides Comprehensive Testing of All Known Breast Cancer Genes

Since 1994, many thousands of women with breast cancer from families severely affected with the disease have been tested for inherited mutations in BRCA1 and BRCA2 by the Myriad Genetics test. The vast majority of those patients were told that their gene sequences were normal. With the development of modern genomics sequencing tools, the discovery of additional genes implicated in breast cancer, and the change in the legal status of genetic testing for BRCA1 and BRCA2 due to the June 13, 2013 U.S. Supreme Court decision to bar the patenting of naturally occurring genes that ended Myriad’s monopoly on the testing for BRCA1 and BRCA2 mutations, it is now possible to determine how often families in these circumstances actually do carry cancer-predisposing mutations in BRCA1, BRCA2, or any of a number of breast cancer-associated genes, despite the results of their previous genetic tests. This was the challenge addressed by Mary-Claire King (photo), Ph.D., American Cancer Society Professor of Medicine and Genome Sciences at the University of Washington, Seattle, past President of the ASHG, and renowned breast cancer genetic researcher; and Tomas Walsh, Ph.D., Associate Research Professor of Medical Genetics, also at the University of Washington, Seattle. The researchers conducted complete genomic sequencing of all genes known to be implicated in breast cancer on DNA samples from breast cancer patients who had normal BRCA1 and BRCA2 commercial test results (Myriad testing). The commercial testing occurred because the patients had a severe family history of breast cancer, defined as a family with three or more relatives affected by breast or ovarian cancer. The results were presented today by Dr. Walsh at the American Society of Human Genetics 2013 annual meeting in Boston.

Rare Mutations in RINT1 Tumor Suppressor Gene Associated with Early-Onset Breast Cancer and Possibly Other Cancers

An international team of scientists has identified an association between heritable, rare mutations in the RINT1 gene and increased risk of early-onset breast cancer, according to research reported today (October 24) at the American Society of Human Genetics (ASHG) 2013 Annual Meeting in Boston. The rare mutations in RINT1, a tumor suppressor gene, were detected in 3 of 49 families participating in a study that sequenced the whole exome, the protein-coding DNA, of families with multiple individuals affected by breast cancer. “Although mutations in RINT1 are rare, it is most likely that the remaining unknown breast cancer susceptibility genes will account for similar small proportions of the disease,” said Daniel J. Park, Ph.D., who presented the study at ASHG 2013 and is Senior Research Fellow in genetic epidemiology at the University of Melbourne, Australia. Only approximately 35 percent of the familial risk for breast cancer has been explained so far, according to Dr. Park and his collaborators, who added that the discovery of the RINT1 variants’ association with the disease could help members of families with multiple cases of breast cancer to identify their individual risk for developing the cancer. Dr. Park’s collaborators in the search for unidentified breast cancer susceptibility genes are scientists at the Institute Curie in Paris, the International Agency for Research on Cancer in Lyon, France, the Huntsman Cancer Institute in Salt Lake City, Utah, as well as the University of Melbourne.