Diagnostics & Imaging Week Washington Editor and Staff Reports

The Agency for Healthcare Research and Quality announced Monday that a review of studies that examined correlations between two genes and a patient's propensity to develop deep-vein thromboses (DVTs) offered at best only skimpy support for the notion of the predictive power of gene tests, leading the authors of the study to conclude that randomized, controlled studies are needed to establish whether doctors can make care recommendations based on the results of those tests.

However clich d the recommendation of "further studies indicated" may seem, the matter is of intense interest, given that DVTs can send chunks of clots to the lungs to form pulmonary embolisms, which the AHRQ statement says is responsible for at least 20,000 deaths in the U.S. each year. Still, a firm that makes genetic testing for the two genes in question is of the view that the results of such tests are not particularly meaningful outside the context of a clinical visit during which a provider can talk to a patient about lifestyle risks that exacerbate any inherited propensity toward DVTs.

Diagnostics & Imaging Week spoke with Martin Munzer, President/CEO of Cygene Labs (Coral Springs, Florida), a firm that makes gene-testing equipment, as well as with the company's director of product development, Keith Zucker, PhD.

Zucker said that the two genes named in the AHRQ statement, Factor V Leiden (FVL) and prothrombin G20210A, "are two of the four we have on the Cygene panel" for DVT risk.

Zucker also noted that "there are hundreds of articles on both those genes," examining their risk independently and jointly, and that despite the cautiousness expressed in the AHRQ statement, there is "no question that they do increase the risk and significantly."

As for the report's attempt to develop a large-scale validation of the joint predictive power of FVL and G20210A, Zucker stated that Cygene's equipment is not sold for "testing in that manner. We're using the [genes] as a risk factor. In that respect, there's no question that the science is very strong."

Martin also said "this is an area of genetics that is very well understood." He acknowledged that the rates of incidence "are not as high as a statistician would like to see," but observed that the mortality level in connection with DVTs is too high to ignore. He characterized the test, which he said the company sells for $89, as a preventive measure. "This is the kind of seat belt you would want to wear" to help avoid DVTs, he said.

The AHRQ report notes that "as many as 600,000 Americans each year may have" DVTs and that hospitals report almost 260,000 pulmonary embolisms annually. AHRQ director Carolyn Clancy, MD, said in the statement that "while genetic testing shows great promise to improve treatment and prevent disease, this report clearly shows that we need more research and evidence to achieve its full potential." Clancy also said that patients "can help reduce their likelihood of developing a blood clot by talking with their doctor about precautions."

CDC gives guidelines for genetic testing

The Centers for Disease Control and Prevention (CDC; Atlanta) has issued the first federal government recommendations to foster accuracy and appropriate use of DNA-based genetic tests.

The guidance document, titled "Good Laboratory Practices for Molecular Genetic Testing for Heritable Diseases and Conditions," which is posted on the CDC's website, addresses considerations for clinical and laboratory professionals that are important for achieving patient benefits and avoiding medical mistakes when molecular genetic tests are used, such as ensuring proper test method selection and test performance and appropriate test result reporting, interpretation and use.

The guidance also covers factors to consider before introducing new tests and what qualifications laboratory personnel should have to perform testing.

Molecular genetic testing is one of the most rapidly growing areas of laboratory testing in the U.S., with the number of genetic diseases and conditions for which tests are available tripling from 423 in the past eight years to more than 1,300, officials said.

The CDC noted that the growth of direct-to-consumer testing, which is permitted in 37 states and often done without oversight, has "raised additional concern about the potential misuse of genetic tests."

DNA-based genetic tests are used to help make decisions about patient care, such as whether patients have or may be at risk for a genetic disease such as cystic fibrosis or whether they may be prone to chronic diseases including cancer, diabetes and blood clotting disorders.

"Getting an accurate diagnosis influences a patient's course of treatment and how they deal with a disease or disease threat," the CDC said. "Implementation of the genetic testing guidance can improve accurate diagnoses and ultimately ensure that patients and their doctors can make the best decisions for their health."