Pathogenic and Likely Pathogenic Germline Variation in Patients with Myeloid Malignancies and Their Unrelated HLA-matched Hematopoietic Stem Cell Donors

Aims: The revised 2022 World Health Organization classification recognizes myeloid neoplasms with associated germline predisposition as a defined subcategory, underscoring the clinical significance of likely pathogenic (LPV) and pathogenic (PV) germline variation in these diseases. To better understand the role of LPV/PV in blood or marrow transplants (BMT), a curative therapy for myeloid neoplasms, we measure their frequency and association with mortality in two cohorts of donor-recipient pairs. Methods: LPV/PV frequencies in 665 cancer-related genes were measured using exomechip genotyping data in 1990 acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients and their unrelated donors, registered with the Center for International Blood and Marrow Transplant Research. Cox proportional hazard models were used to test variant association with recipient mortality one-year post-transplant. Results: Thirteen autosomal dominant (AD) LPV/PV in eight genes were found in 2.8% of patients and 2.2% of donors; those linked to autosomal recessive conditions appeared in 11.1% of patients and 11% of donors. The most common AD LPV/PV mutations in recipients were found in DDX41 (n = 18). For donors, the most frequent AD PVs occurred in CHEK2 (n = 21) and Fanconi Anemia (FA) genes (n = 7). DDX41 and CHEK2 variation did not correlate with patient survival, but patients with donors with an LPV/PVs in an FA gene had lower survival (HR = 2.38, 95%CI: 1.06-5.31, P = 0.035) than patients whose donors did not have an FA LPV/PV. Conclusion: We identified LPVs/PVs in cancer genes in donors and recipients and are the first to show an association of donor FA PVs with mortality after BMT.