Constitutional chromosomal abnormality identified in a sibling donor after bone marrow stem cell transplantation in a pediatric patient with acute megakaryoblastic leukemia

Clonal cytogenetic abnormalities in donor-derived cells after sex mismatched allogeneic stem cell transplantation

Clonal cytogenetic abnormalities (CCA) in donor-derived cells after stem cell transplant (SCT) are typically reported in donor-derived cell neoplasms, but CCA also may reflect a constitutional abnormality in the donor or may be present in a recipient without overt hematological malignancy. We reviewed 8515 tests on 2035 patients, who had allogenic sex mismatched SCT and underwent serial cytogenetic analysis between 2006 and 2020 in our institution. A constitutional CCA was observed in 3 patients: inv(10), t(1;5), and t(13;14). A somatic CCA without overt neoplasia was detected in 12 patients: del(7q) (n = 6), del(20q) (n = 3), der(11)t(11;11) (n = 1), t(1;9) (n = 1), dup(6p)(n = 1). In this group, four patients with cytopenia had del(7q), and an association between del(7q) and an adverse overall survival (OS) was observed [HR:5.99; 95%CI 1.23-29.92). Four patients had a donor-derived cell neoplasm: myelodysplastic syndrome (n = 3) and acute myeloid leukemia (n = 1), and all four neoplasms had loss of 7q. In our cohort, ∼1% of the patients (19/2,035) had CCA in donor-derived cells. Balanced constitutional CCA can pose a reproductive risk to donor. Loss of 7q is the most common somatic CCA, in donor-derived cells.