Are you sure the patient is a CYP2D6 ultra-rapid metabolizer?

AIM: This study investigated the possible cause of false positive detection of CYP2D6 gene duplication (CYP2D6XN) using the standard TaqMan-based real-time PCR assay from Thermo Fisher Scientific.

METHODS: Used samples of two copy carriers as control to evaluate the effect of sample storage condition and the reference genes with respect to test accuracy.

RESULTS: The standard test from Thermo Fisher Scientific produced false positive results of the CYP2D6XN detection when samples were exposed to high temperature and high humidity. The unbalanced template stability between the CYP2D6 testing target and the RNase P reference target was likely the source of error. The problem was reduced but not eliminated when the telomerase reverse transcriptase gene was used as the reference.

CONCLUSION: Special care is required in sample handling, testing and data verification to ensure accurate test results and avoid misdiagnosis of an individual as a CYP2D6 ultra-rapid metabolizer.