Validation and clinical application of transactivation assays for RUNX1 variant classification

• Published in: Blood advances 2022-06, Vol.6 (11), p.3195-3200
• Main Authors: Decker, Melanie, Agarwal, Anupriya, Benneche, Andreas, Churpek, Jane, Duployez, Nicolas, Duvall, Adam, Ernst, Martijn P.T., Förster, Alisa, Høberg-Vetti, Hildegunn, Hofmann, Inga, Nash, Michelle, Raaijmakers, Marc H.G.P., Tvedt, Tor H.A., Vlachos, Adrianna, Schlegelberger, Brigitte, Illig, Thomas, Ripperger, Tim
• Format: Article
• Language: English
• Subjects: Blood Platelet Disorders - genetics; Core Binding Factor Alpha 2 Subunit - genetics; Core Binding Factor Alpha 2 Subunit - metabolism; Germ Cells; Humans; Leukemia, Myeloid, Acute - genetics; Stimulus Report; Transcriptional Activation
• ISSN: 2473-9529; 2473-9537
• DOI: 10.1182/bloodadvances.2021006161

Familial platelet disorder with associated myeloid malignancies (RUNX1-familial platelet disorder [RUNX1-FPD]) is caused by heterozygous pathogenic germline variants of RUNX1. In the present study, we evaluate the applicability of transactivation assays to investigate RUNX1 variants in different regions of the protein. We studied 11 variants to independently validate transactivation assays supporting variant classification following the ClinGen Myeloid Malignancies Variant Curation Expert Panel guidelines. Variant classification is key for the translation of genetic findings. We showed that new assays need to be developed to assess C-terminal RUNX1 variants. Two variants of uncertain significance (VUS) were reclassified to likely pathogenic. Additionally, our analyses supported the (likely) pathogenic classification of 2 other variants. We demonstrated functionality of 4 VUS, but reclassification to (likely) benign was challenging and suggested the need for reevaluating current classification guidelines. Finally, clinical utility of our assays was illustrated in the context of 7 families. Our data confirmed RUNX1-FPD suspicion in 3 families with RUNX1-FPD-specific family history, whereas for 3 variants identified in RUNX1-FPD-nonspecific families, no functional defect was detected. Applying functional assays to support RUNX1 variant classification can be essential for adequate care of index patients and their relatives at risk. It facilitates translation of genetic data into personalized medicine. •Transactivation assays are appropriate for functional characterization of the majority of RUNX1 missense variants observed in RUNX1-FPD.•Implementation of transactivation assays for RUNX1 variants with unknown function accelerates their translation into clinical care.