AML pathognomonic chromosomal rearrangements were also detected using fluorescence-activated cell sorting (FACS) in immunophenotypically defined HSCs (CD34+CD38−) and hematopoietic progenitor cells (CD34+CD38+) in primary MDS and AML at diagnosis and at relapse [31,32]. The gene discussed is CD38; the disease is myelodysplastic syndrome.