Clinical impact of ENIGMA-based variant reclassification on genotype-phenotype analyses in BRCA1- and BRCA2-associated hereditary breast and ovarian cancer.

BRCA1/2

Re-evaluation of BRCA1 and BRCA2 variants using ENIGMA consensus recommendations after initial classification by the ACMG 2015 criteria, with comparison of clinicopathological data before and after reclassification

Accurate interpretation of BRCA1 and BRCA2 variants underpins genotype-phenotype correlations and clinical decisions, yet general frameworks such as the ACMG 2015 criteria often leave many variants of uncertain significance, which can generate misleading clinicopathological associations and complicate genetic counselling. The authors retrospectively analysed 3,706 individuals from a large Turkish cohort tested for BRCA1 and BRCA2 because of BRCA-related malignancies; variants were first classified according to the ACMG 2015 criteria and then re-evaluated using ENIGMA consensus recommendations. Pathogenic or likely pathogenic variants were detected in 6.7% of patients and 3.8% were initially classified as variants of uncertain significance; after ENIGMA-guided reclassification, a substantial proportion of these variants, particularly missense variants lacking functional impact, were reclassified as benign or likely benign. The clinicopathological differences observed between ACMG-defined pathogenic and uncertain-significance groups (age at onset, tumour distribution, receptor status, progression-free survival) disappeared after ENIGMA-based reassessment, revealing biological heterogeneity within the variant of uncertain significance category. The authors conclude that ENIGMA-guided interpretation improves analytical precision, reduces false-positive associations and provides a more reliable framework for genetic counselling and risk assessment.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

The useful message is methodological: under ACMG 2015 criteria alone, the pathogenic and uncertain-significance groups differed in age at onset, tumour distribution, receptor status and progression-free survival, and these differences vanish after ENIGMA reclassification, showing how a heterogeneous variant of uncertain significance category can produce misleading associations. The abstract, however, quantifies neither the number of variants reclassified nor the number of patients whose management would change, which is what would give the work its clinical reach, and it states neither whether the cohort is single-centre or multicentre nor how large the compared groups are. On an exome or a genome, it is a reminder that annotation under a consensus framework such as ENIGMA is a step in its own right, not a detail, although generalisation to other populations remains to be shown.

Analysis by Dr Thibaut Benquey