African DNA linked to prostate cancer

[Guest guest]

Risky Legacy: African DNA linked to prostate cancer

Ben Harder

The high rate of prostate cancer among African American men may result

in large part from a newly identified stretch of DNA passed down from

their African ancestors.

A black man's odds of developing prostate cancer by age 55 are more than

twice those of a white man. The racial discrepancy is less pronounced

when the disease appears later. Researchers have suspected for years

that genetic factors account for part of the racial difference in risk.

Most African Americans have both African and European forebears, so

their chromosomes are mosaics of genes from the two continents.

Previously identified genetic markers indicate that in U.S. blacks, an

average of about 80 percent of the DNA is African in origin.

Geneticists have long hypothesized that they could identify

disease-causing chunks of DNA by sifting through the genomes of

ethnically mixed populations and noting where people with a disease

tend to have genes from the same ancestral source, says Reich of

Harvard Medical School in Boston. Recent technical advances have made

this approach feasible.

Reich and his colleagues analyzed the genomes of nearly 1,600 African

Americans who had developed prostate cancer. In those men, a portion of

chromosome 8 containing nine known genes was more frequently of African

origin than were other portions of the DNA.

When the team tested nearly 900 cancer-free African American men,

African ancestry of DNA turned up no more frequently in the implicated

portion of chromosome 8 than elsewhere in their genomes.

http://www.sciencenews.org/articles/20060826/fob2.asp