"In light of our findings, the marker's ability to identify statin responders is also in doubt," said Assimes. "Until very large-scale studies are performed to directly test the marker's ability to identify statin responders, I would not withhold statins from patients just because their KIF6 test was negative."

The finding's larger message is that more caution is warranted when using genetic markers to guide health care. There's understandably great desire to use the information about human genetics that's been amassing since the sequencing of the human genome 10 years ago, said Quertermous, who has worked in the field for more than 20 years. "It's something I've been waiting for, for a long time."

That's because the well-known risk factors for atherosclerosis, such as high cholesterol, smoking, diabetes and high blood pressure, appear to account for only about half the variation of rates of coronary disease observed in human populations. The balance of variation is likely explained by a combination of inherited variants in or near genes that are important in the pathogenesis of disease in addition to other unrecognized, adverse environmental exposures.

"Using genetics to help improve our ability to predict coronary disease is particularly important because we have several different classes of drugs at our disposal that can substantially reduce the risk of heart attacks" said Assimes. "But we still need to be careful about what we put into practice and not get carried away too quickly. We know from previous experience that a positive association between a genetic variant and a common disease, such as coronary disease, needs to be consistently observed in many human population studies before it can be believed."

In fact, Quertermous points out that even for the roughly one dozen genetic markers that have been successfully validated to date, evidence to support their use in clinical practice is lacking. However, this situation will likely change in the near future as researchers reliably identify more genetic markers.

Source: Stanford University Medical Center