Scientists at deCODE Genetics and academic collaborators from Iceland, The Netherlands, Spain, Denmark, Germany, Sweden, the USA, the UK and Romania today report the discovery of a variant in the sequence of the human genome associated with risk of developing basal cell carcinoma of the skin (BCC), as well as prostate cancer and glioma, the most serious form of brain cancer.  The study was done in collaboration with Illumina, Inc., and is published today in the online edition of Nature Genetics.

Using Illumina sequencing technology, deCODE scientists determined the sequences of the entire genomes of 457 Icelanders, and identified 16 million single nucleotide polymorphisms (SNPs). Through a combination of SNP genotyping and computational techniques utilizing the extensive Icelandic genealogy, they were able to propagate those 16 million variants into over 40,000 Icelanders for use in this study.

The researchers discovered a single letter variant located in TP53, a gene known to play a central role in tumor biology and for accumulating so called somatic mutations, during the development of cancer in patients.  Until now, however, individuals who are born with defective copies of the gene (germline variants) have been found extremely rarely, only in families with cancer predisposition syndromes, Li Fraumeni syndrome (LFS) and Li-Fraumeni-like syndrome (LFL). The variant found in the present study is an unusual type of mutation that appears to affect the way the gene’s messenger RNA is processed; the messenger RNA in patients with the mutant TP53 gene appears to lack proper termination and polyadenylation.

This is the first evidence of a germline variant in TP53 associated with cancer predisposition beyond LFS and LFL. While the mutations causing LFS and LFL syndromes are very rare (occuring 1:5,000 to 1:20,000 births), the variant described in this paper occurs in ~ 1 in 25 individuals in Iceland, and at comparable frequencies in US and UK populations.

“This mutation is one of a growing number of deCODE discoveries of relatively low frequency sequence variants with large effect,” said Kari Stefansson, deCODE’s CEO and senior author of the study.  “The discovery of such variants is made possible through the breadth and quality of the data that the Icelandic population provides.”

Dr. Stefansson emphasized, “We will, together with our collaborators, including Illumina, extend ourselves to turn this discovery into benefit for patients and those at risk of cancer.”

BCC is the most common cancer in people of European ancestry. Sun exposure is the primary risk factor for BCC, but genetic predisposition also plays a substantial role.   Until now, no mechanistic causal connection between cancers as diverse as BCC, prostate cancer, glioma, and colorectal adenoma was known.

The paper, “A Germline Variant in the TP53 Polyadenylation Signal Confers Cancer Susceptibility” is published online in Nature Genetics at www.nature.com/ng and will appear in an upcoming print edition of the journal.

Analysis of four SNPs, in tandem with genetic risk factors detected by the deCODE ProstateCancer™ test, yields substantial improvement in efficacy of PSA screening

Scientists from deCODE genetics and academic colleagues from Iceland, the UK, US, Netherlands, Spain and Romania today report the discovery of a set of single-letter variations in the sequence of the human genome (SNPs) that impact individual baseline levels of prostate specific antigen, or PSA. Testing for PSA levels is the most commonly used screening tool for the detection of prostate cancer. A prostate biopsy is routinely recommended for men with PSA above a certain threshold. However, PSA levels can rise for reasons unrelated to prostate cancer and baseline healthy levels vary substantially between individuals, resulting in many men without cancer being biopsied while cancer in others is not detected. The paper published today demonstrates that analysis of four SNPs can be used to derive a personalized PSA threshold that more accurately identifies those men who are more likely to have a positive biopsy and for whom one should therefore be recommended.

“This is straighforward genetics with direct clinical utility. Detected early, prostate cancer can be treated with near total success. The challenge is to more effectively risk stratify the population, identifying and biopsying those at high risk and with aggressive disease while minimizing the number of negative biopsies we perform. And using the genetics we are improving the sensitivity and specificity of PSA testing. Like virtually every protein in the body, PSA levels vary between individuals according to SNPs that regulate gene expression. The SNPs reported today enable us to personalize PSA thresholds, thereby changing the recommendation on whether to biopsy for a substantial proportion of men. Moreover, the discriminatory power of testing for these SNPs is highest when done in tandem with the SNPs associated directly with risk of the disease measured by our deCODE ProstateCancer™ test. We are working to swiftly incorporate these PSA markers into our testing portfolio,” said Kari Stefansson, CEO of deCODE and senior author on the study.

The paper, entitled “Genetic correction of PSA values using sequence variants associated with PSA levels,” is published today online in Science Translational Medicine and will appear in an upcoming print edition of the journal. The study was conducted in several stages and involved tens of thousands of men with and without prostate cancer. First, more than 300,000 SNPs were analyzed in 16,000 Icelandic men with PSA measurements but who had never been diagnosed with prostate cancer. SNPs that correlated with PSA levels were identified and then validated in a cohort from the UK. These SNPs were then studied in large case-control cohorts from Iceland, the Netherlands, Spain, Romania and the US to establish the association with PSA levels independent of risk of prostate cancer itself. The authors then demonstrated how measuring four SNPs correlated with PSA levels can be used to obtain a personalized threshold for when to biopsy, and that using such thresholds improves the ratio of positive to negative biopsies. The greatest improvement in prediction accuracy was seen when men were tested both for the PSA correction SNPs as well as a panel of prostate cancer risk SNPs detected by the deCODE ProstateCancer™ test.

deCODE and the authors wish to thank the thousands of participants who took part in this study. It was funded in part by grant 202059 (PROMARK) and grant 218071 (CancerGene), both from the 7^th Framework Program of the European Union.

deCODE genetics and ARUP Laboratories today announced a partnership  through which ARUP will offer deCODE’s DNA-based prostate cancer risk assessment test  to its clients nationwide.

Under the terms of the non-exclusive agreement, ARUP will integrate deCODE ProstateCancer™ into the portfolio of tests it offers to leading academic medical centers, public and private healthcare providers, and major hospitals across the United States. ARUP’s clients will order the test, submit samples and receive results through ARUP, with deCODE conducting the genetic analysis in its CAP and CLIA-certified laboratory.

deCODE ProstateCancer measures 25 common single-letter variations, or SNPs, in the sequence of the human genome that are associated with the risk of prostate cancer. These SNPs were validated in tens of thousands of patients and controls in many populations. The risk conferred by these common SNPs is independent of family history, and does not correlate with benign prostatic hyperplasia (a non-cancerous enlargement of the prostate). The test can identify approximately 15% of men in the general population who are at double the average risk of prostate cancer as well as 5% who have triple the average risk. This test is complementary to standard clinical risk screening, including PSA, providing additional information for a more complete and personalized picture of individual risk to help doctors manage effective screening and early-detection strategies.

“The management of patients with elevated or borderline PSA continues to be a challenge, and having the additional knowledge of a patient’s genetic risk for prostate cancer can be very useful. We are pleased to be working with deCODE, who has developed this test through a number of large clinical studies and continues to demonstrate excellent scientific productivity in the area of human genetics,” said Edward Ashwood, MD, President and CEO of ARUP Laboratories.

“We are excited to be partnering with ARUP to increase the availability of our prostate cancer test to physicians and their patients. The quality and breadth of their services, and their range of customers across the healthcare spectrum, make them an excellent partner. Our test helps to meet the need for improved risk stratification and patient outcomes, and we believe that this alliance will make these benefits available to a greater number of patients,” said Kari Stefansson, Executive Chairman and President of Research at deCODE.

ARUP Laboratories plans to begin offering deCODE’s prostate cancer risk test (ARUP test code 2003326) to clients in the fall of 2010.

deCODEme Complete Scan now includes Testicular Cancer

At deCODEme, we believe that when it comes to planning your preventive health efforts, your genetic profile is the place to start. This month we have added two new diseases, both of which are highly curable if caught early.

If you are a deCODEme customer who has bought our Complete Scan, your account now includes a personalized genetic risk assessment for:

Testicular Cancer of males, and Ovarian Cancer of females.

Our scientists have also added more genetic details to the risk assessment for Prostate Cancer, which now includes a total of 25 genetic risk variants for customers of the Complete Scan.

deCODEme Prostate Cancer

Last night we announced our discovery of four more SNPs linked to increased risk of prostate cancer. At the same time, academic collagues in the US and UK have also found more SNPs. (See article in TIMES ONLINE) All of the well-validated new risk variants will be incorporated into your deCODEme profile in the days ahead.

In the same study we published yesterday, we also conducted an analysis of all well-validated genetic risk factors discovered to date to establish what percentage of men would be at a significantly higher risk than average using these markers. Based upon our ability to swiftly conduct a population-based analysis in Iceland, this analysis demonstrates that about 4% of men are at more than double average risk based upon these risk factors, while just over 1% are at more than 2.5-times average risk.
Average lifetime risk of prostate cancer in Iceland is very similar to that of other populations of European descent, at about 12%. In light of the above calculations, that means that about 4% of men are at more that 20% lifetime risk based upon currently known risk SNPs, while slightly more than 1% of men are at more than 30% lifetime risk. Other standard measures of risk, such as age, family history, and PSA score, are all independent of the risk measured by common genetic risk factors, and so complement this risk calculation.

All of this is important to bear in mind as you check your own risk profile and consider what this information might mean to your health. Those of us who are deCODEme subscribers may well have wondered what it means when new risk factors are found, incorporated into our risk calculations, and your risk score changes. The answer is that for the vast majority of us, our increased risk of these common diseases is either slightly above or slightly below average. The numbers may change slightly, but this may not have any immediate bearing on how you should try to protect your health. At the same time, because these diseases are common, average risk is rarely insignificant, so we are none of us off the hook.

Yet it is for those in the highest risk categories that your profile may provide information that you can take to your doctor, and with him or her consider other risk factors you may have and evaluate how best to lower that risk or undergo appropriate screening.

As ever, we are eager to hear how you use your profile and how it may be helping you to take more control over your health. For our part, we will continue to integrate the best in genetics into your profile.

With best regards,
Edward Farmer
The deCODEme Team

Charles Wallace and his wife believe that a deCODEme Complete Scan helped save Chuck's life when it lead to discovering Prostate Cancer. Click on the picture to see Chuck's story.

Dr. Bradley Bale at the the Heart Attack & Stroke Prevention Center is a big believer in deCODE’s tests for genetic risk factors for cardiovascular disease. As he has for many of his patients, Dr. Bale recommended that Charles Wallace, a 55 year-old Texan, have a full deCODEme scan to understand his risk of a range of conditions, including cardiovascular diseases. The breadth of the risk factors analyzed by deCODEme proved to be very important indeed. Mr. Wallace learned that he was at nearly double the average risk of prostate cancer, a piece of information he and Bale followed up on and that Wallace credits with helping to save his life.

These latest SNPs are the fourth set of variants that deCODE has linked to prostate cancer risk. They are single-letter variations in the genome – SNPs – located on chromosome 2 and on the X chromosome. The SNPs confer relatively modest increases in risk – of approximately 20% and 15% per copy carried, respectively – but because they are also quite common they are each believed to contribute to about 5% of prostate cancer cases. They were found through the analysis of 300,000 SNPs in 23,000 Icelanders in deCODE’s prostate cancer studies, and then confirmed in an analysis of more than 15,500 individuals from seven different cohorts from Europe and the United States.

Published studies by major academic research groups in the United States and Europe have over the past month provided strong validation of the role of the other common risk variants, on chromosomes 8 and 17, discovered by deCODE in 2006 and 2007. Altogether, the prostate cancer risk variants now included in deCODEme™ contribute to more than 50% of all cases of the disease. Because of these variants, 10% of men are at twice the risk and 1% of men are at three times the risk of the disease in the general population.

For those subscribers who believe they should consider having a DNA-based diagnostic test for prostate cancer risk variants that they can use with their doctor, deCODE has also just launched deCODEPrCa™, the first such test aimed at understanding individual risk of the disease.