deCODE and Radboud Discovery in Bladder Cancer May Link Disease Risk and Somatic Mutations in Tumors
News Mar 31, 2010
Sequence variants associated with cancer have to date fallen into two distinct categories. Variants in the ordinary, or “germline,” sequence of the genome that is passed between generations were linked to risk of disease, while “somatic” mutations were found in tumor cells as these cells run amok.
deCODE genetics and Radboud University Nijmegen Medical Centre in the Netherlands have announced a discovery that appears to bridge this divide. Their scientists, in collaboration with the Leeds Institute of Molecular Medicine, have identified a novel, common single-letter variant (SNP) on chromosome 4p16 that confers risk of urinary bladder cancer, but also confers risk of a somatic mutation in the FGFR3 gene, which is known to occur in UBC and to promote the growth of what are mainly low-grade, non-invasive tumors.
“This discovery is exciting because it offers us a truly unique window to a more holistic view of the genetic contribution to the pathogenesis of a common form of cancer. This is compelling from the point of view of therapeutic development. About half of all UBC cases are low grade and treatment is usually successful. But the disease frequently recurs, which makes treatment costly and would make a drug that could reduce the need for invasive procedures a valuable tool for patients and the healthcare system,” said Kari Stefansson, executive chairman and president of research at deCODE and senior author on the paper.
This is the fifth SNP linked to risk of UBC in multiple populations, and the fourth discovered under the deCODE-Radboud collaboration. The study analyzed genotypic data from more than 50,000 patients and controls from a dozen countries, and found that those who carry the ‘T’version of the chromosome 4 SNP are at approximately 25% greater risk of developing UBC per copy carried than are non-carriers. The 5% of people who are at highest risk from this combination of five markers are at approximately 60% greater than average risk of UBC. Since the average lifetime risk of UBC is about 4% for men in the United States, those with the highest risk constellation of these markers would be at a roughly 6.5% risk of the disease.
The study, ‘A sequence variant at 4p16.3 confers susceptibility to urinary bladder cancer,’ is published online in Nature Genetics and will appear in an upcoming print edition of the journal.
Urinary bladder cancer is estimated to be the 9th most common cancer world-wide and the 13th most common cause of death from cancer. Every year, some 70,000 people in the United States are diagnosed with bladder cancer, and more than 14,000 people will die of the disease. Bladder cancer has been linked to exposure to various types of toxic substances such as cigarette smoke and industrial chemicals. Incidence of bladder cancer varies considerably between ethnicities, and as the risk factors reported here were discovered by analyzing DNA from groups of European descent, it is our hope that the publication of these findings will contribute to the swift analysis of the impact of these variants in cohorts of other continental ancestries.