For instance, a recent study demonstrated thatchromothriptic disruption of a gain-of-function mutation in CXCR4 in hematopoietic stem cells (HSCs) was curative in a patientwith warts, hypogammaglobulinemia, immunodeficiency, and myelokathexis (WHIM)syndrome as a result of preferential expansion of the CXCR4-haploinsufficient HSCsin the bone marrow niche [28]. Here, CXCR4 is linked to immunodeficiency disease.