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Genetic variation on breast cancer
risk is subject of study
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“Having an extra copy of certain genes may be either detrimental or protective in relation to certain conditions, depending on the function of that particular gene.”
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A UB researcher is investigating the genetic mechanism underlying the association of a specific estrogen receptor and breast cancer risk, funded by an $856,979 five-year career development award from the National Cancer Institute.
Heather Ochs-Balcom, assistant professor of social and preventive medicine and lead researcher on the project, will study a type of genetic variation that represents new territory for the study of breast cancer genetics.
“We are exploring a newly recognized source of genetic diversity that is inherited, called copy number variation, that has not been widely studied as of yet,” says Ochs-Balcom, a genetic epidemiologist in the School of Public Health and Health Professions.
“We are examining whether the difference in the number of copies of the estrogen receptor-alpha gene, called ESR1, influences breast cancer risk, and whether the amount of inherited copies of this gene correlates to the number of copies present in their own breast cancer tumors.”
Breast cancer tumors already are known to exhibit copy number variation in this gene, and information about the expression of the estrogen receptor currently is used to help guide treatment.
“An example of more familiar copy number variation is trisomy 21, or Down syndrome, characterized by an extra whole copy of chromosome 21,” Ochs-Balcom notes. “We are examining copy number variation on a much, much smaller scale—at the single gene level. Having an extra copy of certain genes may be either detrimental or protective in relation to certain conditions, depending on the function of that particular gene.”
The researchers will use data from approximately 1,100 cases and 2,100 healthy controls enrolled in the Western New York Exposures and Breast Cancer study (WEB study), as well as 480 African-American cases and 1,900 healthy controls who were recruited nationally to take part in the Women’s Health Initiative (WHI). UB was a Clinical Vanguard Center site for this landmark trial.
“We have a unique opportunity to study a large group of African-American women, in collaboration with the WHI, to see if there is an association of this genetic variation and breast cancer risk,” says Ochs-Balcom. “African-American women have a different distribution of breast cancer tumor types, so the association may differ.”
Jo Freudenheim, professor and chair of the Department of Social and Preventive Medicine and principal investigator on the WEB study, is Ochs-Balcom’s primary mentor for the career development award. Other mentors include Norma Nowak, director of scientific planning at UB’s New York State Center of Excellence in Bioinformatics and Life Sciences and director of its DNA Microarray and Genetics Facility, and Robert Elston, professor and director of the Division of Genetic and Molecular Epidemiology at Case Western Reserve University in Cleveland. Peter Shields, director of Cancer Genetics and Epidemiology at Georgetown University Medical Center, will consult on the project and provide some of the specific genetic analysis and genotyping.
Jean Wactawski-Wende, professor and associate chair of social and preventive medicine and vice provost for strategic initiatives at UB, will help guide Ochs-Balcom’s work with the WHI portion of the study. Lara Sucheston, assistant professor of biostatistics, is also a significant contributor to the WHI research.
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