By Eleanor Griffith

Once Burned, Twice Shy: Cardiovascular Genetics Clinicians Exercise Caution in Relying on Received Variant Classifications

At the recent 2017 Heart Rhythm Society conference, the clinical and counseling challenges posed by Variants of Uncertain Significance (VUS) was, not unexpectedly, a recurring theme, as were discordant classifications between laboratories and ordering clinicians.

By ACMG Guidelines, 90% certainty is sufficient to warrant a classification of “likely pathogenic.” The same guidelines acknowledge that “at present, most variants do not have data to support a quantitative assignment of variant certainty” and point to the need for “statistical approaches to objectively assign pathogenicity confidence to variants.”

The ACMG guidelines also stress that the clinical application of genetic testing evidence is also dependent on the clinical context and indication for testing: “It is therefore critical for referring healthcare providers to communicate with the clinical laboratory to gain an understanding of how variants are classified to assist in patient counseling and management.”

At Phosphorus, we take a conservative and transparent approach to variant classification, making an effort to provide the data and the rationale behind the classification on the issued report and by strictly following ACMG guidelines. We would always prefer to receive as much information as possible about the individual or family you have identified as appropriate for testing–even if it doesn’t fit on a test requisition form. We welcome discussion with ordering providers at all points in the testing process.

We are looking for ways to facilitate better and easier communication: between ordering clinicians and the lab regarding phenotypic and family history information; between GCs and referring physicians; between clinicians working in multidisciplinary teams; between clinicians and their patients. Let us know how we can best partner with you to help you optimally manage your patients!

Eleanor is the Clinical Science Liaison at Phosphorus. You can reach her at to share ideas for improved partnership.

1.Genet Med. 2015 May; 17(5): 405–424. Published online 2015 Mar 5. doi: 10.1038/gim.2015.30

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