Experts warn about genetic tests

HONG KONG | Wed Oct 13, 2010 9:12am EDT

(Reuters) - Medical experts warned consumers in comments published on Wednesday to be cautious about genetic tests that purport to predict various diseases, saying they added little value beyond what consumers already knew.

Risk factors like smoking, lack of exercise, age, hypertension and family history were usually more reliable predictors, said researchers in Australia, who published their comment in a paper in PLoS Medicine.

“Studies done for diabetes, heart disease and common cancers have identified a large number of genes associated with increased risk of developing (these diseases),” said lead author Wayne Hall, a professor at the University of Queensland Center for Clinical Research.

“But the liability and increased risk of any one of these genes is often trivially small … it's not information you can act on,” he said by telephone.

There have been long-term studies tracking large numbers of people over time to see if those with certain gene mutations go on to develop associated diseases, but Hall said such genetic information was no more superior in predicting disease.

“In general, adding the genetic information doesn't improve on the ability to predict over and above what you know about existing risk factors,” he said.

“So knowing that you smoke, blood pressure, your gender, family history and age; they are still good predictors of disease risk and genetic information usually doesn't do as well as those fairly crude predictors of disease risk.”

The note of caution comes as consumers are swamped with offers of genetic tests – many on the Internet – that purport to predict many different kinds of diseases.

“I wouldn't purchase any of these tests myself. They have very limited use and if I have reason to suspect I have some gene that is strongly predictive of disease risk, I will go through a proper genetic testing curriculum because there is very little value in these genome-wide scans that are being marketed,” Hall said.

Hall was making a distinction between facilities with trained clinical geneticists who can interpret and give advice and counseling before and after a result is known, and companies which merely hand over the result.

(Reporting by Tan Ee Lyn; Editing by Sugita Katyal)

http://www.reuters.com/article/idUSTRE69B67420101013