NEW YORK – The Association for Molecular Pathology and other expert groups on Thursday published a set of consensus recommendations for standardizing clinical CYP2D6 genotyping assays.
The document was authored by members of AMP's Pharmacogenetics Working Group along with members of the College of American Pathologists, the Dutch Pharmacogenetics Working Group of the Royal Dutch Pharmacists Association, and the European Society for Pharmacogenomics and Personalized Therapy and published in the Journal of Molecular Diagnostics.
The group recommended a minimum set of alleles and their defining variants that should be included in all clinical CYP2D6 genotyping tests, which it called Tier 1, as well as a list of optional alleles that don't currently meet the criteria for inclusion in the first list, Tier 2.
The authors used a variety of criteria to make the lists, including allele frequencies in multiethnic populations, functional impact of the variant alleles, the availability of reference materials, and the technical feasibility of clinical laboratories to detect the variant. According to the authors, Tier 1 recommendations include the majority of known non-wild-type CYP2D6 variation in major ethnic groups.
The document also noted the recommendations should not be interpreted as a restrictive list and should be implemented with other clinical guidelines, including ones issued by the Clinical Pharmacogenetics Implementation Consortium.
"CYP2D6 is known to be responsible for the metabolism of many commonly prescribed medications including some antidepressants, atypical and typical antipsychotics, beta-blockers, opioids, antiemetics, and atomoxetine," Victoria Pratt, chair of the AMP PGx Working Group, said in a statement. "While the CYP2D6 gene is especially complex, with this latest report, we have been able to define a minimum set of variants that should be included in all future clinical CYP2D6 PGx genotyping assays."
The guidelines build on previous recommendations for clinical genotyping of CYP2C19, CYP2C9, and genes for warfarin testing. Standardizing PGx tests "will improve concordance across laboratories and enable healthcare professionals to provide high-quality patient care," AMP President Antonia Sepulveda said in a statement.