BALTIMORE, Jan. 17 (UPI) -- U.S. and Swedish researchers identified gene markers for hereditary prostate cancer that appear to raise prostate cancer risk by more than nine times.

The study, published in the New England Journal of Medicine, found that the gene markers are common and could account for nearly half of the prostate cancer cases in the study.

William B. Isaacs of the Johns Hopkins Brady Urological Institute and colleagues at Wake Forest University in Winston-Salem, N.C., and the Karolinska Institute in Sweden drew blood from 2,893 prostate cancer patients and 1,781 men without the disease.

White blood cells are a good source of DNA that an individual is born with as opposed to DNA in cancer cells that gets altered by the environment or other means, Isaacs explained.

Using DNA from blood cells, the researchers sifted through nucleotides, or so-called "single nucleotide polymorphisms," or SNPs.

The researchers found 16 SNPs in five different regions of human chromosomes 8 and 17 that were more common to men with prostate cancer than men without the disease.