GENETIC TEST FOR HEART DISEASE AND CANCER RISK

Customers who order DecodeMe’s genetic tests receive the kit pictured above. The black wand is scraped against the inside of the cheek to collect cells for DNA analysis.From car makers to cosmetic surgeons, everyone is scrambling to develop and market more economical products--and the consumer-genetics industry is no exception. DecodeMe, a division of Iceland-based Decode Genetics, launched two new services this week: a test that detects genetic variations associated with different cardiovascular diseases, and a screen that detects genetic variations linked to the risk of developing various cancers. At $195 and $225, respectively, the new tests are cheaper than Decode's genome-wide screen, which for $985 assesses genetic risk for 34 diseases and traits ranging from diabetes to male-pattern baldness. "We wanted to give people an opportunity to buy a test that would only address their needs," says Kari Stefansson, Decode's president and cofounder.

But the same question that has plagued direct-to-consumer genetic testing since its inception remains: the clinical utility of such screens. "We have not sorted out what the best approach is for dealing with prostate-cancer risk in the normal population, much less in those who are at some increased risk," says James Evans, a physician and geneticist at the University of North Carolina at Chapel Hill. He says that the same is true for other types of cancer.

The first test--deCODEme Cardio--detects eight genetic variations, known as single-nucleotide polymorphisms (SNPs), associated with the risk of heart attack, intracranical and abdominal aortic aneurysm, stroke and atrial fibrillation, peripherial arterial disease, and venous thromboempolism (clots in blood vessels). The second test--deCODEme Cancer--measures 29 SNPs associated with the risk of prostate, lung, bladder, colorectal, and breast cancers, as well as basal cell carcinoma.

The variations detected by the Decode tests clearly do increase risk of these diseases--in most cases, the link has been replicated numerous times. But they each boost risk of disease by a modest amount: typically 20 percent or less. In contrast, mutations in the BRCA1 gene, which physicians often screen for in women with a family history of breast cancer, boost a woman's risk of developing breast cancer to between three and seven times that of someone who lacks the mutation. While the latter can help physicians recommend preventative measures, such as a mastectomy, it's not yet clear how common variations of moderate effect can help shape an individual's plan for prevention or treatment of disease.

BEST SPERM FOR THE JOB

Ranking sperm cells could improve the odds of in vitro fertilization.Alistair Elfick demonstrates a technology called Raman spectroscopy, which uses laser light to identify chemical changes--in this case, it finds sperm with the best DNA.Some approaches to in vitro fertilization involve mixing sperm and egg in a test tube and letting nature take its course. But in about half of all infertility cases, a problem with the man's sperm may require a more direct method. In these cases, a different process, called intracytoplasmic sperm injection (ICSI), in which a single sperm cell is injected directly into an egg, is sometimes used. With this one-shot opportunity, it's important to choose a sperm cell with the best potential for success. A team at the University of Edinburgh, Scotland, has now announced a new technique to ensure that the best sperm win: analyzing their DNA for potential damage beforehand, and choosing those that are structurally sound.

"It's a new development that could be very promising," says Alan Penzias, a reproductive endocrinologist at Boston IVF and Harvard Medical School, who was not involved in the research. Penzias explains that current standards for choosing a single sperm cell for an ICSI procedure usually depend on assessing how well the sperm swims; if none of the sperm can swim, a chemical test can find those that are intact and alive. "It's been really pretty crude," he says. 

Alistair Elfick, lead scientist for the Edinburgh team, explains that by choosing a single sperm rather than allowing many sperm to swim to and compete for a place in the egg, "you have very much become the arbiter of the quality of that sperm. So clearly, there's a motivation to have a more rigorous selection procedure." With this new technique, the researchers can rank different sperm and choose the one with the most intact DNA. "The endpoint we're moving towards is having a score of DNA quality," Elfick says. But he adds that the approach is an overall measure of the sperm's health; it's not sensitive enough to pick and choose traits.

The method that Elfick and his colleagues developed relies on Raman spectroscopy, a technique that measures the way that molecules scatter photons from a beam of laser light, revealing the molecules' vibrational properties. In order to probe a single sperm cell with Raman spectroscopy, the researchers first pin it down with optical tweezers--a focused laser beam that is able to "trap" a small object like a living cell. The unique scattering produced by each molecule creates a fingerprint of the contents in a sample, allowing scientists to analyze its chemical makeup. In this application, the researchers use Raman spectroscopy to look at the structure of a sperm cell's DNA and determine whether that DNA is broken or intact. Elfick explains that when DNA breaks, a chemical group forms at the ends of the breaks, and they can be detected with Raman spectroscopy.