Navigation Links
Discovery suggests location of genes for breast density, a strong risk factor for breast cancer

PHILADELPHIA − Studying the DNA of 889 people, gene hunters at the Mayo Clinic and H. Lee Moffitt Cancer Centers have identified a region on chromosome 5p that is significantly associated with dense breast tissue, a known risk factor for breast cancer. The findings, published in the September 1 issue of Cancer Research, a publication of the American Association for Cancer Research, suggest that genes which influence breast density could serve as a predictive marker for disease and provide a biological target for agents that may reduce breast cancer risk by reducing breast density.

Women with dense breasts meaning the breast has a smaller proportion of fat relative to stromal and epithelial tissues − are three to five times more likely to develop breast cancer than women with less dense breasts, according to the researchers. Scientists have estimated the total influence of genes on breast density to be about 60 percent.

The study, the first reported genetic linkage analysis for genes influencing breast density, provides further evidence that this trait does appear to be genetically influenced, said the studys lead investigator, Celine Vachon, Ph.D., an epidemiologist at the Mayo Clinic in Rochester, Minnesota.

Although the investigators have strong evidence that a gene residing in this chromosomal region influences breast density, the exact gene that is responsible is not yet known. One or more of the 45 candidate genes in this region could explain a large proportion of mammographic breast density, and potentially, breast cancer, she said.

Within the region on chromosome 5p, the gene which encodes the prolactin receptor in particular, stands out as a possible contributor to dense breasts. Prolactin is a hormone that helps enlarge mammary glands during pregnancy and, after childbirth, is involved in milk production. Previous research has found a correlation between mammographic density and prolactin levels in postmenopausal women, the researchers note.

Vachons team took what they term an agnostic approach to uncovering genes, or gene regulators like microRNA, that are involved in the development of dense breasts. We assume we dont know anything about the biology of the trait and we let the genomes of our participants and their breast densities guide us, Vachon said.

Their method contrasts the traditional candidate gene approach, where scientists look at variations in specific genes thought to be involved with the disease or trait of interest. Such linkage studies have been used to uncover many high-impact risk genes, such as the breast cancer susceptibility genes BRCA1 and BRCA2.

The Mayo researchers performed a genome-wide linkage scan to identify possible chromosome regions in 89 families, part of a multi-generational Minnesota family study that began in 1944 at the University of Minnesota. Blood samples and mammograms were collected and analyzed for 756 female participants; 133 men were also included to help clarify genetic information in their offspring, mothers and sisters. We used the relationship between family members and breast density to inform where a gene might be, Vachon says.

Researchers first studied 403 DNA markers spaced across the genome to determine the amount of genetic information shared at and between each of these genomic signposts and its correlation to breast density as measured on mammography. They found three regions of interest, and narrowed the most promising region further by studying 21 additional, more densely spaced DNA markers. This secondary analysis highlighted one region consisting of approximately 45 known genes on chromosome 5p that was significantly associated with increased breast density.

The researchers then adjusted their analysis to eliminate the contribution of body mass index (BMI), which is a known breast cancer risk factor and also inversely associated with breast density, and found the signal was just as strong. That means the location that we have identified on chromosome 5p does not appear to affect breast density through its influence on BMI, she said.

Only age, diagnosis of abnormal cells on a breast biopsy and inheritance of rare breast susceptibility genes, such as BRCA1 and BRCA2, are stronger risk predictors of breast cancer than is breast density, Vachon said.

At this point, we have not identified a gene or genes for breast density but a promising location to investigate further, Vachon said. Identification of genes for breast density will improve our understanding of how breast density influences breast cancer development in women.

In this study we focused on the genetics of a risk factor for cancer. This approach has not been tried before, said Thomas Sellers, Ph.D., a coauthor on this study and currently director of the Moffitt Research Institute in Tampa, Florida.

Contact: Greg Lester
American Association for Cancer Research

Related medicine news :

1. Discovery of bone gene
2. Latest discovery on Autism
3. Bacterial discovery may help CF patients
4. A new discovery about Acetaminophen
5. A new discovery about Acetaminophen
6. Resistant tumors could be treated with the discovery of a new molecule within cancer cells
7. Treatment for cholesterol-related illnesses likely with the discovery of receptor in mice
8. Ways to counter radiation effects with new molecule discovery
9. Canada stunned as mad cow discovery leads to beef ban
10. Mouth Infection better handled with new discovery
11. New discovery made about the Nipah Virus
Post Your Comments:
(Date:11/27/2015)... ... November 27, 2015 , ... The rapid speed at ... people age, more care is needed, especially with Alzheimer’s, dementia and other cognitive ... being overworked. The forgotten part of this equation: 80 percent of medical care ...
(Date:11/27/2015)... ... November 27, 2015 , ... An inventor, ... to dispense prescription medications at home, so he invented the patent-pending ELECTRONIC M.D. ... dispense prescription medications. In doing so, it could help to prevent potential overdose ...
(Date:11/27/2015)... ... 27, 2015 , ... Lizzie’s Lice Pickers just announced a special promotion that ... of their purchase of lice treatment product. In addition, customers will receive a complimentary ... spokesperson. “Finding lice is a sure way to ruin the holidays, so we encourage ...
(Date:11/27/2015)... ... November 27, 2015 , ... ProSidebar: Fashion is a set ... With ProSidebar: Fasion, video editors can easily add an informative sidebar to any ... opener. Utilize presets featuring self-animating drop zones, lines, bars, and text with the ...
(Date:11/27/2015)... ... November 27, 2015 , ... ... through sharing, the 2016 Building Better Radiology Marketing Programs meeting will ... on Sunday, March 6, 2016, at Caesars Palace in Las Vegas with a ...
Breaking Medicine News(10 mins):
(Date:11/26/2015)... FRANCISCO , November 26, 2015 ... billion by 2022, according to a new report by Grand ... Chronic Kidney Disease (CKD) which demands kidney transplantation is expected ... and cost effective substitute for organ transplantation. --> ... billion by 2022, according to a new report by Grand ...
(Date:11/26/2015)... --> ... att använda SyMRI för att hitta optimal ... med multipel skleros (MS) eller hjärntumörmetastaser och ... för att kunna använda SyMRI Research Edition ... kan man generera flera konstrastbilder från en ...
(Date:11/26/2015)... DUBLIN , Nov. 26, 2015 ... the addition of the "2016 Future Horizons ... Monitoring (TDM) Market: Supplier Shares, Country Segment Forecasts, ... offering. --> ... comprehensive analysis of the Italian therapeutic drug monitoring ...
Breaking Medicine Technology: