Wave of genetic testing creates 'patients-in-waiting'

Should doctors start treating these patients early?

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The increased use of genetic testing is creating a population of "patients-in-waiting" who have been diagnosed with genes for a potentially fatal disease, but show no symptoms of illness, the Wall Street Journal's Amy Dockser Marcus reports.

A growing number of Americans are finding out if they face a higher-than-average risk of potentially fatal genetic conditions, including cystic fibrosis, hypertrophic cardiomyopathy, and Pompe disease.

Some patients are diagnosed as high-risk at birth, while other are diagnosed later in late when referred for genetic testing. When performing such tests, physicians are required to check for irregularities on more than 50 other genes, according to new guidelines issued by the American College of Medical Genetics. This means patients being testing for genetic susceptibility to one disease may find they are at high risk of another.

Example: Waiting for cystic fibrosis

The growing number of patients-in-waiting for cystic fibrosis has prompted a new name for the condition when it is asymptotic: Cystic Fibrosis Transmembrane Conductance Regulator-Related Metabolic Syndrome (CRMS).

The Cystic Fibrosis Foundation says there 841 known cases of CRMS in the United States, but specialists believe the numbers are higher. In 2009, the foundation helped physicians create guidelines for CRMS patients, including guidance for how frequently the patients should be monitored.

At the cystic-fibrosis clinic at Children's Hospital Los Angeles, caregivers are tracking 250 patients, and 70 of those patients are considered patients-in-waiting. "What do I do with these patients?" asks Children's pulmonologist Danieli Salinas.

Should doctors start treatment early?

Many physicians believe patients-in-waiting should be treated for the disease as a preventive measure.

Priya Kishnani, chief of medical genetics at Duke University Medical Center, administers drugs to patients with genes for the rare Pompe disease, even though many of them do not exhibit any symptoms. "To me, this is like you are sitting on a time bomb, a time bomb that can detonate," Kishnani says.

For patients with a genetic risk for hypertrophic cardiomyopathy, physicians may even recommend having a defibrillator implanted, according to Calum MacRae, clinical director of the genomic medicine at Brigham and Women's Hospital.

"In a condition that may never emerge, it's hard to justify," MacRae says, adding that he takes into account the patient's age and health, as well as their tolerance for living in medical limbo, before suggesting such a move. He notes that some patients with the gene worry more after a family member suffers a sudden cardiac arrest, so doctors "end up having to base the decision to treat on gestalt" (Dockser Marcus, Journal, 11/18).

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