Samples from 7 patients (6 BP, 1 AP) resulted in 35.8% ± 7.3% marrow human CD45+ (hCD45+) cell chimerism and recapitulated numerous clinical features (3) of MPN-BP within 4 months of transplantation, including the presence of at least 20% hCD45dimCD33+ or hCD34+ cells (Supplemental Figure 1A) or at least 20% blasts, as detected by morphological examination of the BM and spleen. The gene discussed is PTPRC; the disease is myeloproliferative disorder.