One finding revealed that in competitive repopulation experiments, hemizygous CXCR4 (Cxcr4+/o) HSCs presented a stable proliferation without depleting long-term hematopoietic stem cells (LT-HSCs), indicating that partial inactivation of CXCR4 may be a strategy to promote HSC engraftment in patients who have WHIM syndrome (Cxcr4+/S338X) after transplantation [57]. This evidence concerns the gene CXCR4 and WHIM syndrome.