Evidence-based recommendations for gene-specific ACMG/AMP variant classification from the ClinGen ENIGMA BRCA1 and BRCA2 Variant Curation Expert Panel.

The ENIGMA research consortium develops and applies methods to determine clinical significance of variants in hereditary breast and ovarian cancer genes. An ENIGMA BRCA1/2 classification sub-group, formed in 2015 as a ClinGen external expert panel, evolved into a ClinGen internal Variant Curation Expert Panel (VCEP) to align with Food and Drug Administration recognized processes for ClinVar contributions. The VCEP reviewed American College of Medical Genetics and Genomics/Association of Molecular Pathology (ACMG/AMP) classification criteria for relevance to interpreting BRCA1 and BRCA2 variants. Statistical methods were used to calibrate evidence strength for different data types. Pilot specifications were tested on 40 variants and documentation revised for clarity and ease of use. The original criterion descriptions for 13 evidence codes were considered non-applicable or overlapping with other criteria. Scenario of use was extended or re-purposed for eight codes. Extensive analysis and/or data review informed specification descriptions and weights for all codes. Specifications were applied to pilot variants with pre-existing ClinVar classification as follows: 13 uncertain significance or conflicting, 14 pathogenic and/or likely pathogenic, and 13 benign and/or likely benign. Review resolved classification for 11/13 uncertain significance or conflicting variants and retained or improved confidence in classification for the remaining variants. Alignment of pre-existing ENIGMA research classification processes with ACMG/AMP classification guidelines highlighted several gaps in the research processes and the baseline ACMG/AMP criteria. Calibration of evidence strength was key to justify utility and strength of different data types for gene-specific application. The gene-specific criteria demonstrated value for improving ACMG/AMP-aligned classification of BRCA1 and BRCA2 variants.

Congenital Hypodysfibrinogenemia due to γ326Cys→Tyr Mutation: Third Ever-Described Case Associated with Recurrent Venous Thrombosis and COVID Vaccine.

INTRODUCTION: Congenital fibrinogen disorders are a heterogenous group of fibrinogen defects. CASE PRESENTATION: Here, we describe hypodysfibrinogenemia in a 33-year-old female patient with provoked recurrent deep vein thrombosis (DVT) diagnosed based on decreased functional and antigenic fibrinogen levels with a decreased functional/antigenic fibrinogen ratio. Definitive diagnosis of congenital hypodysfibrinogenemia is done by genotyping using whole-exome sequencing, which identified the γ326Cys→Tyr mutation combined with single-nucleotide polymorphisms: rs2070011 and rs2070018 in FGA and rs1049636 in FGG. Fibrin structure assays showed reduced maximum polymerization rate. The mother of the proband shares the same γ326Cys→Tyr mutation and experienced a provoked DVT. CONCLUSION: Our case with DVT is the third ever-described occurrence of the mutation γ326Cys→Tyr that is associated with hypodysfibrinogenemia. The mechanism by which this mutation induces thrombosis remains unknown. Due to the high recurrence risk of thrombosis, the patient was treated with long-term reduced dose of rivaroxaban (10 mg daily) as secondary prophylaxis.