Understanding_hematopoietic_stem_cell_mobilization_and_engraftment_

This study looks at patients undergoing gene therapy for genetic blood and immune disorders, in particular sickle cell disease. From each patient, single blood HSPC colonies are grown from patient blood mononuclear cells, bone marrow mononuclear cells, or CD34+ at multiple time points: pre gene transduction, post-transduction, and post-infusion (at several time points). Whole-genome sequencing will be performed on DNA from these colonies and somatically-acquired mutations will be called. Using these mutations, a phylogeny of these cells can be inferred and further inferences can be made about the gene therapy transduction and engraftment steps.

Type: Whole Genome Sequencing
Archiver: European Genome-Phenome Archive (EGA)

1 Dataset 1 Publication

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Dataset ID	Description	Technology	Samples
EGAD00001010913	While gene therapy (GT) provides a potentially curative treatment option for patients with sickle cell disease (SCD), the occurrence of myeloid malignancies in clinical trials has prompted concern. To interrogate potential mechanisms underlying increased cancer risk, we used hematopoietic stem cell (HSC) clonal tracking by whole genome sequencing (WGS) to map the somatic mutation and clonal landscape of 2,592 gene modified as well as unmodified single stem and progenitor cells from six SCD patients undergoing gene therapy (7-26 years old, average 12.7× depth). Pre-GT phylogenetic trees in SCD were highly polyclonal and mutation burdens per cell were elevated in some, but not all, patients. Post-GT, no clonal expansions were identified. However, an increased frequency of driver mutations associated with myeloid neoplasms or clonal hematopoiesis (DNMT3A- and EZH2-mutated clones in particular) were seen in both genetically modified and unmodified cells suggested positive selection of mutant clones during gene therapy. This work sheds light on the mutation landscape and HSC clonal dynamics in gene therapy for SCD and highlights enhanced fitness of some HSCs harboring pre-existing driver mutations following gene therapy. Future studies should define the long-term fate of mutant clones including any contribution to expansions associated with myeloid neoplasms.	Illumina NovaSeq 6000	3394

Publications	Citations
Clonal selection of hematopoietic stem cells after gene therapy for sickle cell disease. Spencer Chapman M, Cull AH, Ciuculescu MF, Esrick EB, Mitchell E, Jung H, O'Neill L, Roberts K, Fabre MA, Williams N, Nangalia J, Quinton J, Fox JM, Pellin D, Makani J, Armant M, Williams DA, Campbell PJ, Kent DG. Nat Med 29: 2023 3175-3183	1