AML/MDS defined by germline DDX41 CV represents a unique entity with favorable outcome
Germline DDX41 CV predisposing patients to MN are often associated with somatic DDX41 mutations
Germline DDX41 variants are the most common mutations predisposing to acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) in adults, but the causal variant (CV) landscape and clinical spectrum of hematologic malignancies (HM) remain unexplored. Here, we analyzed the genomic profiles of 176 HM patients carrying 82 distinct presumably germline DDX41 variants among a group of 9,821 unrelated patients. Using our proposed DDX41 specific variant classification, we identified features distinguishing 116 HM patients with CV from 60 HM patients with variant of uncertain significance (VUS): an older age (median 69 years), male predominance (74% in CV versus 60% in VUS, P=0.03), frequent concurrent somatic DDX41 variants (79% in CV versus 5% in VUS, p<0.0001), a lower somatic mutation burden (1.4 ± 0.1 in CV versus 2.9 ± 0.04 in VUS, P=0.012), near exclusion of canonical recurrent genetic abnormalities including mutations in NPM1, CEBPA and FLT3 in AML, and favorable overall survival (OS) in AML/MDS patients. This superior OS was determined independent of blast count, abnormal karyotypes, and concurrent variants, including TP53 in AML/MDS patients, regardless of patient's sex, age or specific germline CV, suggesting that germline DDX41 variants define a distinct clinical entity. Furthermore, unrelated patients with myeloproliferative neoplasm (MPN) and B-cell lymphoma were linked by DDX41 CV, thus expanding the known disease spectrum. This study outlines the CV landscape, expands the phenotypic spectrum in unrelated DDX41-mutated patients, and underscores the urgent need for gene-specific diagnostic and clinical management guidelines.