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To report BRCA1 and BRCA2 (BRCA1/2) variant reassessments and reclassifications between 2012 and 2017 at the Advanced Molecular Diagnostics Laboratory (AMDL) in Toronto, Canada, which provides BRCA1/2 testing for patients in Ontario, and to compare AMDL variant classifications with submissions in ClinVar. Variants were assessed using a standardized variant assessment tool based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology’s guidelines and tracked in an in-house database. Variants were shared through the Canadian Open Genetics Repository and submitted to ClinVar for comparison against other laboratories. AMDL identified 1209 BRCA1/2 variants between 2012 and 2017. During this period, 32.9% (398/1209) of variants were reassessed and 12.4% (150/1209) were reclassified. The majority of reclassified variants were downgraded (112/150, 74.7%). Of the reclassified variants, 63.3% (95/150) were reclassified to benign, 20.7% (31/150) to likely benign, 10.0% (15/150) to variant of uncertain significance, 2.0% (3/150) to likely pathogenic, and 4.0% (6/150) to pathogenic. Discordant ClinVar submissions were found for 40.4% (488/1209) of variants. BRCA1/2 variants may be reclassified over time. Reclassification presents ethical and practical challenges related to recontacting patients. Data sharing is essential to improve variant interpretation, to help patients receive appropriate care based on their genetic results.

PurposeEfforts have been made by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology to make variant classification more uniform, but many limitations remain. Reclassification of a variant of uncertain significance (VUS) is expected, but other more certain calls, like pathogenic or benign, can also be reclassified once additional information is gathered. Variant reclassification can create difficult circumstances for both patients and clinicians.MethodsRetrospective review of all variant reclassifications in genes associated with hereditary cancer syndromes at one clinic between September 2013 and February 2017 was completed. All variant reclassifications were completed and reported by the original testing laboratory.ResultsA total of 1,103 hereditary cancer tests were ordered. Fewer than 5% (40/1,103) of the initial reports were updated during that time period. Most reclassifications (29/40) were downgrades of VUS to likely benign. Only three reclassifications could potentially alter medical management.ConclusionThe majority of variant reclassifications do not impact medical management. Upgrading a variant call to pathogenic could be important for a patient's care and shows the importance of open communication between laboratories and clinicians. A variant downgrade from pathogenic can be a significant reclassification as well, especially if prophylactic surgery has been completed.