decreased hematopoietic stem cell number absent hematopoietic stem cells 2012-05-11T01:35:28Z MP:0011695 MPheno.ontology absence of the multipotent, self-renewing stem cells found in the bone marrow, yolk sac and the fetal liver; HSCs give rise to all the types of both the myeloid and lymphoid cell lineages absent HSCs csmith