XMEN is an X-linked recessive immunodeficiency characterized by CD4 (186940) lymphopenia, severe chronic viral infections, and defective T-lymphocyte activation (Li et al., 2011). Affected individuals have chronic Epstein-Barr virus (EBV) infection and are susceptible to the development of EBV-associated B-cell lymphoproliferative disorders. Magnesium supplementation may be therapeutic (summary by Li et al., 2014).

Immunodeficiency-36 with lymphoproliferation (IMD36) is an autosomal dominant primary immunodeficiency with a highly heterogeneous clinical phenotype, characterized primarily by recurrent respiratory tract infections, lymphoproliferation, and antibody deficiency. Other features include growth retardation, mild neurodevelopmental delay, and autoimmunity. The major complication is development of B-cell lymphoma (Elkaim et al., 2016).

IMD52 is an autosomal recessive primary immunodeficiency with variable manifestations, including severe combined immunodeficiency, hematologic autoimmune disorders, progressive lymphopenia and hypogammaglobulinemia, and lymphoproliferation with splenomegaly. Patients develop severe recurrent infections from infancy, and most die without bone marrow transplantation. The variable clinical features result from a defect in T-cell receptor signaling (summary by Keller et al., 2016 and Bacchelli et al., 2017).

Immunodeficiency-63 with lymphoproliferation and autoimmunity (IMD63) is an autosomal recessive disorder characterized by immune dysregulation. Affected individuals present in infancy with features of both abnormal activation of certain immune signaling pathways, resulting in lymphoid proliferation, dermatitis, enteropathy, and hypergammaglobulinemia, as well as features of immunodeficiency, such as recurrent infections and increased susceptibility to viral infections, especially CMV. Laboratory studies show increased NK cells that show impaired differentiation, as well as abnormal T cell populations or responses. Some patients may die in childhood; hematopoietic bone marrow transplantation is curative (summary by Zhang et al., 2019).

Immunodeficiency-78 with autoimmunity and developmental delay (IMD78) is an autosomal recessive systemic disorder characterized by onset of symptoms in early childhood. Affected individuals present with features of immune deficiency, such as recurrent sinopulmonary or skin infections, as well as autoimmunity, including autoimmune cytopenias, hemolytic anemia, and thrombocytopenia. Autoimmune hepatitis or thyroid disease and central nervous system vasculitis with stroke may also occur. There is increased susceptibility to bacterial, viral, and fungal infections. Laboratory studies show lymphopenia with advanced differentiation and premature senescence of CD8+ T cells and B cells; some patients may have hypergammaglobulinemia. The findings indicate immune dysregulation. Patients also have global developmental delay with speech delay and variable intellectual disability. Many patients die prematurely, but successful hematopoietic bone marrow transplant may be curative (summary by Lu et al., 2014 and Atallah et al., 2021).

Immunodeficiency-92 (IMD92) is an autosomal recessive primary immunodeficiency characterized by the onset of recurrent infections in infancy or early childhood. Infectious agents are broad, including bacterial, viral, fungal, and parasitic, including Cryptosporidium and Mycobacteria. Patient lymphocytes show defects in both T- and B-cell proliferation, cytokine secretion, and overall function, and there is also evidence of dysfunction of NK, certain antigen-presenting cells, and myeloid subsets. Hematopoietic stem cell transplantation may be curative (summary by Beaussant-Cohen et al., 2019 and Levy et al., 2021).