Individual Hematopoietic Stem Cells in Human Bone Marrow of Patients with Aplastic Anemia or Myelodysplastic Syndrome Stably Give Rise to Limited Cell Lineages

Mutation of the phosphatidylinositol N‐acetylglucosaminyltransferase subunit A (PIG‐A) gene in hematopoietic stem cells (HSCs) results in the loss of glycosylphosphatidylinositol‐anchored proteins (GPI‐APs) on HSCs, but minimally affects their development, and thus can be used as a clonal maker of HSCs. We analyzed GPI‐APs expression on six major lineage cells in a total of 574 patients with bone marrow (BM) failure in which microenvironment itself is thought to be unaffected, including aplastic anemia (AA) or myelodysplastic syndrome (MDS). GPI‐APs‐deficient (GPI‐APs−) cells were detected in 250 patients. Whereas the GPI‐APs− cells were seen in all six lineages in a majority of patients who had higher proportion ([dbmtequ]3%) of GPI‐APs− cells, they were detected in only limited lineages in 92.9% of cases in the lower proportion (