Gene therapy, influence on cardiac death and mortality by Ray Sahelian, M.D. Genetic testing benefit and cost

A gene is a set of segments of nucleic acid that contains the information necessary to produce a functional RNA product in a controlled manner.

Genes behave differently in men and women
Thousands of genes behave differently in the same organs of males and females. This could explain why men and women have different responses to drugs and diseases. Gene expression -- the level of activity of a gene -- varies greatly according to sex. Gene expression holds important implications for understanding disorders such as diabetes, heart disease and obesity, and identifies targets for the development of gender-specific therapies. Even in the same organ, scores of genes varied in expression levels between the sexes. The smallest differences are in brain tissue. Males and females share the same genetic code, but gender regulates how quickly the body can convert DNA to proteins. Aspirin is more effective at preventing heart attack in men than women. One gender may metabolize the drug faster, leaving too little of the medication in the system to produce an effect. Genome Research, July 2007

Genetic testing - a waste of money?
A number of companies now offer tests, typically costing hundreds of dollars, to calculate genetic risks for common conditions like cancer, diabetes and heart disease that involve multiple genes. Genetic tests to determine disease risk are proliferating but many are a waste of money and tell people little more than they would know from studying family history.

Not cost effective for heart disease testing
Gene testing does not help predict the risk of heart disease over existing methods. Doctors "should keep on focusing on what they are doing" and not think that DNA tests are going to change their practice anytime soon, study author Dr. A. Cecile J. W. Janssens from Erasmus MC-University Medical Center Rotterdam, The Netherlands. Dr. A Cecile J. W. Janssens says it would take more than 100 genes to make tests useful, but that researchers have only found about 10 related to heart disease. "For predicting heart disease on the basis of DNA alone, I am very pessimistic, simply because non-genetic risk factors play such an important role," Dr. Janssens said, referring to environmental factors such as diet. American Heart Journal, July 2009.

Gene tests that combined over 100 genetic mutations proved ineffective at predicting a woman's risk of a heart attack or stroke. High cholesterol, high blood pressure and a family history of heart disease were the strongest predictors of a woman's heart disease risk. Journal of the American Medical Association, February 17, 2010.

Breast cancer genes
Women with certain changes in the BRCA1 gene are at high risk for breast cancer. Mutations in the BRCA1 gene can leave cells incapable of repairing routine DNA damage. When such damage occurs in a protein called PTEN, which regulates the growth of cells, cell growth is unchecked and tumors form. Women with imperfect copies of BRCA1 or BRCA2 have a 50 to 85 percent chance of getting breast cancer. Mutations in these genes is responsible for 5 to 10 percent of breast cancer cases.

Risk of mortality, prediction with gene testing
Nine new gene variations have been discovered that can make a person vulnerable to sudden cardiac death. In Feb 2009, Dan Arking of Johns Hopkins University School of Medicine, found a single gene that raises the risk of cardiac death. A March 2009 study identifies that gene plus nine new ones that alter the timing of heart contractions, a measure known as the QT interval. People with prolonged QT intervals have a higher risk of cardiac death. The more of these 10 gene variants a person has, the greater the chances of having a prolonged QT interval.