Immunodeficiency-33 (IMD33) is an X-linked recessive disorder that affects only males. It is characterized by early-onset severe infections, usually due to pneumococcus, H. influenzae, and atypical mycobacteria, although other organisms have also been detected. Immunologic investigations may show variable abnormalities or may be normal. Disturbances include dysgammaglobulinemia with hypogammaglobulinemia, decreased IgG2, aberrant levels of IgM and IgA, and decreased class-switched memory B cells. There is often poor, but variable, response to vaccination; in particular, most patients do not develop antibodies to certain polysaccharide vaccines, notably pneumococcus. Other immunologic abnormalities may include impaired NK cytotoxic function, impaired cytokine production upon stimulation with IL1B (147720) or TNFA (191160), low IL6 (147620), low IL12 (see 161561), and decreased IFNG (147570). Patients do not have overt abnormalities of T-cell proliferation, although signaling pathways, such as CD40LG (300386)/CD40 (109535), may be disturbed. There is heterogeneity in the immunologic phenotype, resulting in highly variable clinical courses, most likely due to the different effects of hypomorphic mutations. Treatment with antibiotics and IVIg is usually beneficial; hematopoietic stem cell transplantation may not be necessary, but can be effective. Features of hypohidrotic ectodermal dysplasia are generally not present, although some patients may have conical teeth or hypodontia (summary by Orange et al., 2004, Filipe-Santos et al., 2006, Salt et al., 2008, Heller et al., 2020).

Immunodeficiency, centromeric instability, and facial dysmorphism (ICF) syndrome is a rare autosomal recessive disorder characterized by facial dysmorphism, immunoglobulin deficiency resulting in recurrent infections, and mental retardation. Laboratory studies of patient cells show hypomethylation of satellite regions of chromosomes 1, 9, and 16, as well as pericentromeric chromosomal instability in response to phytohemagglutinin stimulation (summary by de Greef et al., 2011). For a discussion of genetic heterogeneity of immunodeficiency-centromeric instability-facial anomalies syndrome, see ICF1 (242860).

Immunodeficiency-11A is an autosomal recessive primary immunodeficiency characterized by normal numbers of T and B lymphocytes, but defective intracellular signaling. There is a block in B-cell differentiation with increased numbers of transitional B cells and hypogammaglobulinemia, as well as decreased numbers of regulatory T cells and defects in T-cell function (summary by Greil et al., 2013 and Stepensky et al., 2013).

Immunodeficiency-56 is an autosomal recessive primary immunodeficiency characterized by B- and T-cell defects and variable dysfunction of NK cells. Patients tend to have normal numbers of lymphocytes, but show defective class-switched B cells, low IgG, defective antibody response, and defective T-cell responses to certain antigens (summary by Kotlarz et al., 2013).

X-linked immunodeficiency-98 with autoinflammation (IMD98) is characterized by onset of recurrent infections associated with lymphoproliferation and autoinflammation in the first decade of life. Mostly males are affected; carrier females may have mild symptoms. Laboratory studies show evidence of immune dysregulation, including hypogammaglobulinemia with reduced memory B cells, skewed T-cell subsets, increased levels of proinflammatory cytokines, activated T cells and monocytes, and autoimmune cytopenias, including neutropenia (Aluri et al., 2021; Fejtkova et al., 2022).