Allogeneic Hematopoietic Stem Cell Transplant for Patients With Primary Immune Deficiencies

Inclusion Criteria: * Diagnosis of immunodeficiency or histiocytic disorder including the following: * Severe combined immunodeficiency (SCID - all variants) * Second bone marrow transplant (BMT) for SCID (after graft rejection) * Omenn's Syndrome * Reticular dysgenesis * Wiskott-Aldrich syndrome * Major histocompatibility complex (MHC) Class II deficiency (bare lymphocyte syndrome) * Hyper IgM Syndrome (CD40 Ligand Deficiency) * Common variable immunodeficiency (CVID) with severe phenotype * Chronic Granulomatous Disease (CGD) * Other severe Combined Immune Deficiencies (CID) * Hemophagocytic Lymphohistiocytosis (HLH) * X-linked Lymphoproliferative Disease (XLP) * Chediak-Higashi Syndrome (CHS) * Griscelli Syndrome * Langerhans Cell Histiocytosis (LCH) * Acceptable stem cell sources include: * HLA identical or 1 antigen matched sibling donor eligible to donate bone marrow * HLA identical or up to a 1 antigen mismatched unrelated BM donor * Sibling donor cord blood with acceptable HLA match and cell dose as per current institutional standards * Single unrelated umbilical cord blood unit with 0-2 antigen mismatch and minimum cell dose of \>5 x 10\^7 nucleated cells/kg as per current institutional guidelines * Double unrelated umbilical cord blood units that are: * up to 2 antigen mismatched to the patient * up to 2 antigen mismatched to each other * minimum cell dose of at least one single unit must be ≥ 3.5 x 10\^7 nucle…