Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Major genetic risk factor found for prostate cancer

23.08.2006
Study validates the power of new method in hunt for genetic causes of complex disease

Harvard Medical School researchers have identified a DNA segment on chromosome 8 that is a major risk factor for prostate cancer, especially in African American men. The paper appears in the August 21 electronic edition of the Proceedings of the National Academy of Sciences (also see PNAS's news tip below).

"This paper identifies a genetic risk factor that about doubles the likelihood of prostate cancer in younger African American men," says principal investigator David Reich, PhD, Harvard Medical School assistant professor of genetics with the HMS Department of Genetics and the Broad Institute. "This finding may explain why younger African Americans have an increased risk for prostate cancer than do other populations--and may also explain why this increased risk in African Americans attenuates with older age."

"This is one of the first genetic risk factors found that is responsible for an appreciable fraction of sporadic prostate cancer cases, particularly for the African American population," says lead author Matthew Freedman, Harvard Medical School instructor of medicine at the Dana-Farber Cancer Institute and the Broad Institute "Interestingly, we found that this region also confers risk for prostate cancer for diverse ethnic groups. The actual gene, however, remains to be identified."

The researchers used their newly developed method of "admixture mapping" to screen through the genome in African Americans (who have both African and European ancestry), searching for the segments where individuals with disease have more of one ancestry than the average. The key epidemiological fact is that prostate cancer occurs approximately 1.6-fold times more often in African Americans than in other populations. This prompted the hypothesis that there is a genetic risk factor for prostate cancer that occurs at higher frequency in African than in other populations, and that can be found by searching for a region where the proportion of African ancestry is higher than the genome average.

Reich, Freedman and their colleagues studied 1,597 African Americans with prostate cancer. They found a section of the genome in the patients that had much more than the average proportion of African ancestry, rising from 78 percent to about 85 percent. The risk factor is localized to a tiny fraction (about a thousandth) of the genome, a section on chromosome 8 containing just 9 genes.

A particularly exciting aspect of this work is that in May a separate research team also identified a genetic variant occurring within the same region, which increases risk for prostate cancer. The study by Reich and colleagues makes two additional advances. One important result is that the genetic risk factor is more important for individuals with younger age. Second, they show that the specific genetic variant reported in the earlier paper can explain only at most a small fraction of the increased risk to African Americans. Thus, major unidentified risk factors remain to be found.

Press Tip from the Proceedings of the National Academy of Sciences

Press Summary:
Chromosome Region for African-American Prostate Cancer Risk
A whole genome analysis has revealed a section on chromosome 8 as significantly associated with African-American's increased risk to prostate cancer. African Americans have about a 1.6 higher risk of developing prostate cancer than European Americans; at least part of this difference is likely a result of genetic factors. Taking advantage of recent advances, David Reich and colleagues used admixture mapping to try and find these factors. The concept of admixture mapping is to scan the genes of mixed ancestry populations (such as African Americans, descended from Africans and Europeans over the last 15 generations), searching for regions where the proportion of DNA inherited from one side is unusual. The authors found that a 3.8 million base region of chromosome 8, termed 8q24, substantially increased prostate cancer risk in men who inherited the African ancestry. Interestingly, this increase was greater in men diagnosed before the age of 72, correlating with observations that prostate cancer risk in African Americans attenuates with age. This same region, which contains 9 known genes, was recently identified by linkage analysis. However, the authors found their results cannot be explained by the two genes proposed in the other analysis; therefore, the major risk gene(s) for prostate cancer remain unidentified.
Scientific Summary:
Admixture mapping reveals locus for prostate cancer risk
Admixture mapping entails scanning the genes of mixed ancestry populations to find regions where the proportion of DNA inherited from either ancestral side is unusual compared to the genome-wide average. This technique could be useful in uncovering risk variants, although it has only recently become practical. Matthew Freedman et al. have now applied admixture mapping to find genes for prostate cancer, taking advantage of its markedly increased incidence rates in African American men. Their analysis of 1,597 cancer cases and 873 controls revealed a 3.8 Mb section of chromosome 8, termed 8q24, that contributes to an increased cancer risk in African Americans with African (as opposed to European) ancestry at this region. There is also a highly significant association between risk and age at 8q24, which correlates with epidemiology studies that show that the elevated incidence of prostate cancer in African Americans compared with other populations attenuates with age. A recent linkage analysis also highlighted a risk association in this region, but Freedman et al. report that the previously described alleles only explain a fraction of the admixture signal; therefore 8q24 still contains a major unidentified risk gene for prostate cancer.

John Lacey | EurekAlert!
Further information:
http://www.hms.harvard.edu
http://focus.hms.harvard.edu/2005/Sep30_2005/genomics.shtml

More articles from Life Sciences:

nachricht Discovery of a Key Regulatory Gene in Cardiac Valve Formation
24.05.2017 | Universität Basel

nachricht Carcinogenic soot particles from GDI engines
24.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>