Source: NIH
Source: NIH

In an effort to standardize terminology that characterizes pharmacogenetic functions and phenotypes—toward the ultimate goal of implementing clinical pharmacogenetics as a common part of precision medicine—a study led by researchers at St. Jude Children's Research Hospital has tackled the language barrier that is often an obstacle in enhancing medication safety and effectiveness. The results from the experts' collaborative work were published recently in Genetics in Medicine through an article entitled “Standardizing terms for clinical pharmacogenetic test results: consensus terms from the Clinical Pharmacogenetics Implementation Consortium.”

Pharmacogenetics is focused on how genetics, in particular, genetic variations in single genes, influences how individuals will respond to drugs, including their risk for serious side effects. Now, a national panel of pharmacogenetics experts from clinical laboratories, research, and patient care has sifted through dozens of terms and reached a consensus on a vocabulary for reporting clinical pharmacogenetic test results.

“We hope that establishing standard terminology will encourage more widespread inclusion of pharmacogenetic results in the electronic health records of patients to help realize the promise of precision medicine to individualize patient care,” explained led study author Kelly Caudle, Pharm.D., Ph.D., of the St. Jude department of pharmaceutical sciences and coordinator of the Clinical Pharmacogenetics Implementation Consortium (CPIC).

The research panel used the thiopurine methyltransferase (TPMT) gene as a specific example of how words and standardization are critical for pharmacogenetics. The TPMT gene encodes for an enzyme that degrades thiopurine chemotherapeutic agents. Genetic variances in the TPMT gene sequence means a small percentage of individuals do not produce a functional enzyme—putting them at high risk for serious side effects at standard doses of the drugs.

The St. Jude team was able to identify 14 terms that medical testing laboratories, researchers, and others use to describe the high-risk TPMT variations. The terms included “deficient function,” “no activity,” “homozygous deficient,” and “absent activity.” Using an established consensus-building method that included multiple rounds of surveying, more than 90 percent of participating experts agreed to replace those descriptions with a single term, “poor metabolizer.”

The expert panel reached consensus on one set of terms to describe how gene variations affected function and other standardized terminology to describe how the differences likely impact clinical care, including drug metabolism and transport.

“Inconsistent terms can be confusing to clinicians, laboratory staff, and patients,” said senior author James Hoffman, Pharm.D., an associate member of the St. Jude Pharmaceutical Sciences department. “The lack of standard vocabulary has been a major obstacle to incorporating pharmacogenetic results in the patients' electronic health record to help guide prescribing.”

The standardized pharmacological terms included in the current report have been endorsed by the Association for Molecular Pathology, whose membership includes more than 2,000 laboratory medicine professionals worldwide. The recommendations will be distributed to pharmacogenetic testing laboratories, professional organizations and others, including dozens of institutions and commercial clinical laboratories worldwide that belong to CPIC, the project's sponsor.

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