MedGen

Presence of viable bacteria in the blood. [from HPO]

A lasting absence of total IgG and total IgA and total IgM in the blood circulation, whereby at most trace quantities can be measured. [from HPO]

A mode of inheritance that is observed for traits related to a gene encoded on the X chromosome. [from HPO]

X-linked agammaglobulinemia (XLA) is characterized by recurrent bacterial infections in affected males in the first two years of life. Recurrent otitis is the most common infection prior to diagnosis. Conjunctivitis, sinopulmonary infections, diarrhea, and skin infections are also frequently seen. Approximately 60% of individuals with XLA are recognized as having immunodeficiency when they develop a severe, life-threatening infection such as pneumonia, empyema, meningitis, sepsis, cellulitis, or septic arthritis. S pneumoniae and H influenzae are the most common organisms found prior to diagnosis and may continue to cause sinusitis and otitis after diagnosis and the initiation of gammaglobulin substitution therapy. Severe, difficult-to-treat enteroviral infections (often manifest as dermatomyositis or chronic meningoencephalitis) can be prevented by this treatment. The prognosis for individuals with XLA has improved markedly in the last 25 years as a result of earlier diagnosis, the development of preparations of gammaglobulin that allow normal concentrations of serum IgG to be achieved, and more liberal use of antibiotics. [from GeneReviews]

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). [from OMIM]

The non-syndromic form of a primary immunodeficiency disease characterised by deficient gamma globulins and associated predisposition to frequent and recurrent infections from infancy. Two forms have been described: X-linked represents approximately 85% of the affected patients, and autosomal which includes recessive and dominant cases but is far less frequent. The clinical signs of the two forms are very similar and include recurrent bacterial infections, diarrhoea and skin infections with onset in infancy. Defects in B lymphocyte development and maturation appear to underlie agammaglobulinaemia. Mutations in seven genes have been reported to be related to IA: BTK (Xq21.33-q22), BLNK (10q23.2-q23.33), CD79A (19q13.2), CD79B (17q23), IGHM(14q32.33), IGLL1 (22q11.23), PIK3R1 (5q13.1) and TCF3 (19p13.3). [from SNOMEDCT_US]