Genetic Testing Determines Safety of Anti-Blood-Clotting Treatment

The specimens can be collected at the physician's office or by the patient in his or her home.

Utilizing the polymerase chain reaction (PCR), the test indicates if a patient will respond normally to clopidogrel bisulfate (has the wild type, or normal, CYP2C191 allele) or not normally because of the presence of one or more of four mutated alleles (CYP2C19*2, CYP2C193, CYP2C194 or CYP2C195).

Quest Diagnostics (Madison, NJ, USA) developed the saliva-based test for cardiovascular disease. DNA testing for gene variants that increase the risk of major coronary events in certain patients taking the anticlotting drug clopidogrel bisulfate (Plavix) is performed by Quest Diagnostics for Scripps Health (San Diego, CA, USA) patients before they undergo coronary stent procedures.

Patients who test positive for the mutated alleles may receive alternative treatments based on a variety of factors. These treatments include increased monitoring, an increased dosage of clopidogrel, or the use of alternative therapies such as treatment with Effient (prasugrel), a blood thinner approved by the U.S. Food and Drug Administration (FDA; Silver Spring, MD, USA) in July 2009.

Most of the one million patients who undergo stent procedures in the United States each year receive Plavix to help prevent blood clots that can cause heart attacks and strokes. However, large-scale studies demonstrate that patients with one or more mutated alleles of the Cytochrome (CYP) 2C19 gene are unable to respond properly to Plavix, increasing their risk of death, heart attack, or stroke compared to people with normal alleles. About one third of people of Caucasian descent, and 40 % or more of people of African and Asian descent, possess common polymorphisms in the CYP2C19 gene.

"Our collaboration with Quest Diagnostics represents a landmark program in individualized medicine, based on considerable new data and new choices for one of the most commonly prescribed medications and medical procedures in the world," said Dr. Eric Topol, chief academic officer of Scripps Health.

Quest Diagnostics offers access to diagnostic testing services through its network of laboratories and patient service centers, and provides interpretive consultation through its medical and scientific staff.

Scripps Health is a nonprofit community health system that treats a half-million patients annually. It has five acute-care hospital campuses, as well as home health care services, and an ambulatory care network of physician offices, outpatient centers, and clinics.

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Scripps Health
U.S. Food and Drug Administration