Classic ataxia-telangiectasia (A-T) is characterized by progressive cerebellar ataxia beginning between ages one and four years, oculomotor apraxia, choreoathetosis, telangiectasias of the conjunctivae, immunodeficiency, frequent infections, and an increased risk for malignancy, particularly leukemia and lymphoma. Individuals with A-T are unusually sensitive to ionizing radiation. Non-classic forms of A-T have included adult-onset A-T and A-T with early-onset dystonia.

Bloom syndrome (BSyn) is characterized by severe pre- and postnatal growth deficiency, immune abnormalities, sensitivity to sunlight, insulin resistance, and a high risk for many cancers that occur at an early age. Despite their very small head circumference, most affected individuals have normal intellectual ability. Women may be fertile but often have early menopause, and men tend to be infertile, with only one confirmed case of paternity. Serious medical complications that are more common than in the general population and that also appear at unusually early ages include chronic obstructive pulmonary disease, diabetes mellitus as a result of insulin resistance, and cancer of a wide variety of types and anatomic sites.

Idiopathic pulmonary hemosiderosis is a respiratory disease due to repeated episodes of diffuse alveolar hemorrhage without any underlying apparent cause, most often in children. Anemia, cough, and pulmonary infiltrates on chest radiographs are found in majority of the patients.

Dubowitz syndrome (DS) is a rare multiple congenital syndrome characterized primarly by growth retardation, microcephaly, distinctive facial dysmorphism, cutaneous eczema, a mild to severe intellectual deficit and genital abnormalities.

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.

Transcobalamin II deficiency (TCN2D) is an autosomal recessive disorder with onset in early infancy characterized by failure to thrive, megaloblastic anemia, and pancytopenia. Other features include methylmalonic aciduria, recurrent infections, and vomiting and diarrhea. Treatment with cobalamin results in clinical improvement, but the untreated disorder may result in mental retardation and neurologic abnormalities (summary by Haberle et al., 2009). Hall (1981) gave a clinically oriented review of congenital defects of vitamin B12 transport, and Frater-Schroder (1983) gave a genetically oriented review.

PMM2-CDG, the most common of a group of disorders of abnormal glycosylation of N-linked oligosaccharides, is divided into three clinical stages: infantile multisystem, late-infantile and childhood ataxia–intellectual disability, and adult stable disability. The clinical manifestations and course are highly variable, ranging from infants who die in the first year of life to mildly affected adults. Clinical findings tend to be similar in sibs. In the infantile multisystem presentation, infants show axial hypotonia, hyporeflexia, esotropia, and developmental delay. Feeding problems, vomiting, faltering growth, and developmental delay are frequently seen. Subcutaneous fat may be excessive over the buttocks and suprapubic region. Two distinct clinical courses are observed: (1) a nonfatal neurologic course with faltering growth, strabismus, developmental delay, cerebellar hypoplasia, and hepatopathy in infancy followed by neuropathy and retinitis pigmentosa in the first or second decade; and (2) a more severe neurologic-multivisceral course with approximately 20% mortality in the first year of life. The late-infantile and childhood ataxia–intellectual disability stage, which begins between ages three and ten years, is characterized by hypotonia, ataxia, severely delayed language and motor development, inability to walk, and IQ of 40 to 70; other findings include seizures, stroke-like episodes or transient unilateral loss of function, coagulopathy, retinitis pigmentosa, joint contractures, and skeletal deformities. In the adult stable disability stage, intellectual ability is stable; peripheral neuropathy is variable, progressive retinitis pigmentosa and myopia are seen, thoracic and spinal deformities with osteoporosis worsen, and premature aging is observed; females may lack secondary sexual development and males may exhibit decreased testicular volume. Hypogonadotropic hypogonadism and coagulopathy may occur. The risk for deep venous thrombosis is increased.

X-linked hyper IgM syndrome (HIGM1), a disorder of abnormal T- and B-cell function, is characterized by low serum concentrations of IgG, IgA, and IgE with normal or elevated serum concentrations of IgM. Mitogen proliferation may be normal, but NK- and T-cell cytotoxicity can be impaired. Antigen-specific responses are usually decreased or absent. Total numbers of B cells are normal but there is a marked reduction of class-switched memory B cells. Defective oxidative burst of both neutrophils and macrophages has been reported. The range of clinical findings varies, even within the same family. More than 50% of males with HIGM1 develop symptoms by age one year, and more than 90% are symptomatic by age four years. HIGM1 usually presents in infancy with recurrent upper- and lower-respiratory tract bacterial infections, opportunistic infections including Pneumocystis jirovecii pneumonia, and recurrent or protracted diarrhea that can be infectious or noninfectious and is associated with failure to thrive. Neutropenia is common; thrombocytopenia and anemia are less commonly seen. Autoimmune and/or inflammatory disorders (such as sclerosing cholangitis) as well as increased risk for neoplasms have been reported as medical complications of this disorder. Significant neurologic complications, often the result of a CNS infection, are seen in 5%-15% of affected males. Liver disease, a serious complication of HIGM1 once observed in more than 80% of affected males by age 20 years, may be decreasing with adequate screening and treatment of Cryptosporidium infection.

The phenotypic spectrum of X-linked severe combined immunodeficiency (X-SCID) ranges from typical X-SCID (early-onset disease in males that is fatal if not treated with hematopoietic stem cell transplantation [HSCT] or gene therapy) to atypical X-SCID (later-onset disease comprising phenotypes caused by variable immunodeficiency, immune dysregulation, and/or autoimmunity). Typical X-SCID. Prior to universal newborn screening (NBS) for SCID most males with typical X-SCID came to medical attention between ages three and six months because of recurrent infections, persistent infections, and infections with opportunistic organisms. With universal NBS for SCID, the common presentation for typical X-SCID is now an asymptomatic, healthy-appearing male infant. Atypical X-SCID, which usually is not detected by NBS, can manifest in the first years of life or later with one of the following: recurrent upper and lower respiratory tract infections with bronchiectasis; Omenn syndrome, a clinical phenotype caused by immune dysregulation; X-SCID combined immunodeficiency (often with recurrent infections, warts, and dermatitis); immune dysregulation and autoimmunity; or Epstein-Barr virus-related lymphoproliferative complications.

Hyper-IgM syndrome type 2 (HIGM2) is a rare immunodeficiency characterized by normal or elevated serum IgM levels with absence of IgG, IgA, and IgE, resulting in a profound susceptibility to bacterial infections. For a discussion of genetic heterogeneity of immunodeficiency with hyper-IgM, see HIGM1 (308230).

Type 3 immunodeficiency with hyper-IgM (HIGM3), first described in humans by Ferrari et al. (2001), is characterized by hypogammaglobulinemia with normal or elevated levels of IgM. For a general phenotypic description and a discussion of genetic heterogeneity of immunodeficiency with hyper-IgM, see HIGM1 (308230).

Hyper-IgM syndrome is a condition characterized by normal or increased serum IgM concentrations associated with low or absent serum IgG, IgA, and IgE concentrations, indicating a defect in the class-switch recombination (CSR) process. For a discussion of genetic heterogeneity of immunodeficiency with hyper-IgM, see HIGM1 (308230).

Any selective IgA deficiency disease in which the cause of the disease is a mutation in the TNFRSF13B gene.

Caspase 8 deficiency is a syndrome of lymphadenopathy and splenomegaly, marginal elevation of 'double-negative T cells' (DNT; T-cell receptor alpha/beta+, CD4-/CD8-), defective FAS-induced apoptosis, and defective T-, B-, and natural killer (NK)-cell activation, with recurrent bacterial and viral infections (summary by Madkaikar et al., 2011).

Immunodeficiency-41 is an autosomal recessive complex disorder of immune dysregulation. Affected individuals present in infancy with recurrent viral, fungal, and bacterial infections, lymphadenopathy, and variable autoimmune features, such as autoimmune enteropathy and eczematous skin lesions. Immunologic studies show a defect in T-cell regulation (summary by Goudy et al., 2013).

A form of congenital disorders of N-linked glycosylation characterized by generalized hypotonia, craniofacial dysmorphism (prominent occiput, short palpebral fissures, long eyelashes, broad nose, high arched palate, retrognathia), hypoplastic genitalia, seizures, feeding difficulties, hypoventilation, severe hypogammaglobulinemia with generalized edema and increased resistance to particular viral infections (particularly to enveloped viruses). The disease is caused by loss-of-function mutations in the gene MOGS (2p13.1).

Celiac disease is a systemic autoimmune disease that can be associated with gastrointestinal findings (diarrhea, malabsorption, abdominal pain and distension, bloating, vomiting, and weight loss) and/or highly variable non-gastrointestinal findings (dermatitis herpetiformis, chronic fatigue, joint pain/inflammation, iron deficiency anemia, migraines, depression, attention-deficit disorder, epilepsy, osteoporosis/osteopenia, infertility and/or recurrent fetal loss, vitamin deficiencies, short stature, failure to thrive, delayed puberty, dental enamel defects, and autoimmune disorders). Classic celiac disease, characterized by mild to severe gastrointestinal symptoms, is less common than non-classic celiac disease, characterized by absence of gastrointestinal symptoms.

Adenosine deaminase (ADA) deficiency is a systemic purine metabolic disorder that primarily affects lymphocyte development, viability, and function. The clinical phenotypic spectrum includes: Severe combined immunodeficiency disease (SCID), often diagnosed by age six months and usually by age 12 months; Less severe "delayed" onset combined immune deficiency (CID), usually diagnosed between age one and ten years; "Late/adult onset" CID, diagnosed in the second to fourth decades; Benign "partial ADA deficiency" (very low or absent ADA activity in erythrocytes but greater ADA activity in nucleated cells), which is compatible with normal immune function. Infants with typical early-onset ADA-deficient SCID have failure to thrive and opportunistic infections associated with marked depletion of T, B, and NK lymphocytes, and an absence of both humoral and cellular immune function. If immune function is not restored, children with ADA-deficient SCID rarely survive beyond age one to two years. Infections in delayed- and late-onset types (commonly, recurrent otitis, sinusitis, and upper respiratory) may initially be less severe than those in individuals with ADA-deficient SCID; however, by the time of diagnosis these individuals often have chronic pulmonary insufficiency and may have autoimmune phenomena (cytopenias, anti-thyroid antibodies), allergies, and elevated serum concentration of IgE. The longer the disorder goes unrecognized, the more immune function deteriorates and the more likely are chronic sequelae of recurrent infection.

A few individuals have been diagnosed with intermediate autosomal osteopetrosis (IAO), a form of the disorder that can have either an autosomal dominant or an autosomal recessive pattern of inheritance. The signs and symptoms of this condition become noticeable in childhood and include an increased risk of bone fracture and anemia. People with this form of the disorder typically do not have life-threatening bone marrow abnormalities. However, some affected individuals have had abnormal calcium deposits (calcifications) in the brain, intellectual disability, and a form of kidney disease called renal tubular acidosis.\n\nOther features of autosomal recessive osteopetrosis can include slow growth and short stature, dental abnormalities, and an enlarged liver and spleen (hepatosplenomegaly). Depending on the genetic changes involved, people with severe osteopetrosis can also have brain abnormalities, intellectual disability, or recurrent seizures (epilepsy).\n\nAutosomal recessive osteopetrosis (ARO) is a more severe form of the disorder that becomes apparent in early infancy. Affected individuals have a high risk of bone fracture resulting from seemingly minor bumps and falls. Their abnormally dense skull bones pinch nerves in the head and face (cranial nerves), often resulting in vision loss, hearing loss, and paralysis of facial muscles. Dense bones can also impair the function of bone marrow, preventing it from producing new blood cells and immune system cells. As a result, people with severe osteopetrosis are at risk of abnormal bleeding, a shortage of red blood cells (anemia), and recurrent infections. In the most severe cases, these bone marrow abnormalities can be life-threatening in infancy or early childhood.\n\nIn individuals with ADO who develop signs and symptoms, the major features of the condition include multiple bone fractures after minor injury, abnormal side-to-side curvature of the spine (scoliosis) or other spinal abnormalities, arthritis in the hips, and a bone infection called osteomyelitis. These problems usually become apparent in late childhood or adolescence.\n\nAutosomal dominant osteopetrosis (ADO), which is also called Albers-Schönberg disease, is typically the mildest type of the disorder. Some affected individuals have no symptoms. In affected people with no symptoms, the unusually dense bones may be discovered by accident when an x-ray is done for another reason. \n\nOsteopetrosis is a bone disease that makes bone tissue abnormally compact and dense and also prone to breakage (fracture). Researchers have described several major types of osteopetrosis, which are usually distinguished by their pattern of inheritance: autosomal dominant or autosomal recessive. The different types of the disorder can also be distinguished by the severity of their signs and symptoms.

Immunodeficiency-10 (IMD10) is an autosomal recessive primary immunodeficiency characterized by onset of recurrent infections in childhood due to defective T- and NK-cell function, although the severity is variable. Affected individuals may also have hypotonia, hypohidrosis, or dental enamel hypoplasia consistent with amelogenesis imperfecta (summary by Parry et al., 2016).

Immunodeficiency-9 (IMD9) is an autosomal recessive disorder characterized by early onset of recurrent infections due to defective T-cell activation. Affected individuals also have congenital myopathy resulting in muscle weakness as well as features of ectodermal dysplasia, including soft dental enamel (summary by McCarl et al., 2009).

Congenital generalized lipodystrophy type 4 (CGL4) combines the phenotype of classic Berardinelli-Seip lipodystrophy (608594) with muscular dystrophy and cardiac conduction anomalies (Hayashi et al., 2009). For a general description and a discussion of genetic heterogeneity of congenital generalized lipodystrophy, see CGL1 (608594).

Congenital disorders of glycosylation (CDG), previously called carbohydrate-deficient glycoprotein syndromes (CDGSs), are a group of hereditary multisystem disorders first recognized by Jaeken et al. (1980). The characteristic biochemical abnormality of CDGs is the hypoglycosylation of glycoproteins, which is routinely determined by isoelectric focusing (IEF) of serum transferrin. Type I CDG comprises those disorders in which there is a defect in the assembly of lipid-linked oligosaccharides or their transfer onto nascent glycoproteins, whereas type II CDG comprises defects of trimming, elongation, and processing of protein-bound glycans. CDG1G is a multisystem disorder characterized by impaired psychomotor development, dysmorphic features, failure to thrive, male genital hypoplasia, coagulation abnormalities, and immune deficiency. More variable features include skeletal dysplasia, cardiac anomalies, ocular abnormalities, and sensorineural hearing loss. Some patients die in the early neonatal or infantile period, whereas others are mildly affected and live to adulthood (summary by Tahata et al., 2019). For a general discussion of CDGs, see CDG1A (212065).

Immunoglobulin (Ig) A deficiency (IGAD) is characterized by decreased or absent levels of serum IgA in the presence of normal serum levels of IgG and IgM in a patient older than 4 years of age in whom other causes of hypogammaglobulinemia have been excluded. IgA in the dimeric form is the dominant immunoglobulin in luminal secretions, such as saliva, tears, bronchial secretions, nasal mucosal secretions, and mucous secretions of the small intestine. Individuals with selective IgA deficiency may be asymptomatic or have recurrent sinopulmonary and gastrointestinal infections, allergic disorders, and autoimmune disorders. The diagnosis of IgA deficiency depends on the measurement of monomeric IgA concentrations in serum; thus individuals with IgA deficiency may have IgA in mucosal systems, which may offer some protection (review by Yel, 2010). Genetic Heterogeneity of IgA Deficiency The IGAD1 locus maps to chromosome 6p21. See also IGAD2 (609529), which is caused by mutation in the TNFRSF13B gene (604907) on chromosome 17p11.

Common variable immunodeficiency (CVID) is a clinically and genetically heterogeneous group of disorders characterized by antibody deficiency, hypogammaglobulinemia, recurrent bacterial infections, and an inability to mount an antibody response to antigen. The defect results from a failure of B-cell differentiation and impaired secretion of immunoglobulins; the numbers of circulating B cells are usually in the normal range, but can be low. Most individuals with CVID have onset of infections after age 10 years. CVID represents the most common form of primary immunodeficiency disorders and is the most common form of primary antibody deficiency. Approximately 10 to 20% of patients with a diagnosis of CVID have a family history of the disorder (reviews by Chapel et al., 2008, Conley et al., 2009, and Yong et al., 2009). Genetic Heterogeneity of Common Variable Immunodeficiency Common variable immunodeficiency is a genetically heterogeneous disorder. See also CVID2 (240500), caused by mutation in the TACI gene (TNFRSF13B; 604907); CVID3 (613493), caused by mutation in the CD19 gene (107265); CVID4 (613494), caused by mutation in the BAFFR gene (TNFRSF13C; 606269); CVID5 (613495), caused by mutation in the CD20 gene (112210); CVID6 (613496), caused by mutation in the CD81 gene (186845); CVID7 (614699), caused by mutation in the CD21 gene (CR2; 120650); CVID8 (614700), caused by mutation in the LRBA gene (606453); CVID10 (615577), caused by mutation in the NFKB2 gene (164012); CVID11 (615767), caused by mutation in the IL21 gene (605384); CVID12 (616576), caused by mutation in the NFKB1 gene (164011); CVID13 (616873), caused by mutation in the IKZF1 gene (603023); CVID14 (617765), caused by mutation in the IRF2BP2 gene (615332); and CVID15 (620670), caused by heterozygous mutation in the SEC61A1 gene (609213). The disorder formerly designated CVID9 has been found to be a form of autoimmune lymphoproliferative disorder; see ALPS3 (615559).

Lung fibrosis-immunodeficiency-46,XX gonadal dysgenesis syndrome is characterised by immune deficiency, gonadal dysgenesis and fatal lung fibrosis. So far, it has been described in two sisters born to consanguineous parents. Both karyotypes were normal female (46,XX). No genetic anomalies could be identified by comparative genome hybridization analysis of their genomes or by analysis of genes known to be associated with these types of anomalies.

Any autosomal agammaglobulinemia in which the cause of the disease is a mutation in the CD79B gene.

Syndromic multisystem autoimmune disease due to Itch deficiency is a rare, genetic, systemic autoimmune disease characterized by failure to thrive, global developmental delay, distinctive craniofacial dysmorphism (relative macrocephaly, dolichocephaly, frontal bossing, orbital proptosis, flattened midface with a prominent occiput, low, posteriorly rotated ears, micrognatia), hepato- and/or splenomegaly, and multisystemic autoimmune disease involving the lungs, liver, gut and/or thyroid gland.

Any autosomal agammaglobulinemia in which the cause of the disease is a mutation in the IGLL1 gene.

Any autosomal agammaglobulinemia in which the cause of the disease is a mutation in the BLNK gene.

A syndromic X-linked intellectual disability characterized by moderate intellectual disability, seizures, dysmorphic facial features and in some older patients slowly progressive unsteady gait and progressive weakness that has material basis in variation in the chromosomal region Xq21.33-q23.

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).

Common variable immunodeficiency-8 with autoimmunity is an autosomal recessive disorder of immune dysregulation. Affected individuals have early childhood onset of recurrent infections, particularly respiratory infections, and also develop variable autoimmune disorders, including idiopathic thrombocytopenic purpura, autoimmune hemolytic anemia, and inflammatory bowel disease. The presentation and phenotype are highly variable, even within families (summary by Lopez-Herrera et al., 2012 and Alangari et al., 2012). Immunologic findings are also variable and may include decreased B cells, hypogammaglobulinemia, and deficiency of CD4+ T regulatory (Treg) cells (Charbonnier et al., 2015). For a general description and a discussion of genetic heterogeneity of common variable immunodeficiency, see CVID1 (607594).

Autoinflammation, antibody deficiency, and immune dysregulation (APLAID) is an autosomal dominant systemic disorder characterized by recurrent blistering skin lesions with a dense inflammatory infiltrate and variable involvement of other tissues, including joints, the eye, and the gastrointestinal tract. Affected individuals have a mild humoral immune deficiency associated with recurrent sinopulmonary infections, but no evidence of circulating autoantibodies (summary by Zhou et al., 2012).

Common variable immunodeficiency-10 (CVID10) is an autosomal dominant primary immunodeficiency characterized by childhood-onset of recurrent infections, hypogammaglobulinemia, and decreased numbers of memory and marginal zone B cells. Some patients may develop autoimmune features and have circulating autoantibodies. An unusual feature is central adrenal insufficiency (summary by Chen et al., 2013). For a general description and a discussion of genetic heterogeneity of common variable immunodeficiency, see CVID1 (607594).

Immunodeficiency-22 (IMD22) is an autosomal recessive disorder characterized by the onset of recurrent bacterial, viral, and fungal respiratory, gastrointestinal, and skin infections in infancy or early childhood. Immunologic workup shows severe T-cell lymphopenia, particularly affecting the CD4+ subset, and impaired proximal TCR intracellular signaling and activation. Although NK cells and B cells are normal, some patients may have hypogammaglobulinemia secondary to the T-cell defect. There are variable manifestations, likely due to the severity of the particular LCK mutation: patients may develop prominent skin lesions resembling epidermodysplasia verruciformis, gastrointestinal inflammation, and virus-induced malignancy. The disease can be fatal in childhood, but hematopoietic stem cell transplant (HSCT) may be curative (Hauck et al., 2012; Li et al., 2016; Keller et al., 2023).

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).

Immune dysregulation with autoimmunity, immunodeficiency, and lymphoproliferation (IDAIL) is an autosomal dominant complex immune disorder with highly variable presentation and clinical manifestations. Prominent features include recurrent infections often associated with hypogammaglobulinemia, autoimmune features such as autoimmune cytopenias, and abnormal lymphocytic infiltration of nonlymphoid organs, including the lungs, brain, and gastrointestinal tract, resulting in enteropathy. Laboratory studies often show lymphopenia and abnormal T and B cell subsets. The variable features are a result of impaired function of Treg cells, which play a role in immune homeostasis (summary by Kuehn et al., 2014; Schwab et al., 2018, and Lopez-Nevado et al., 2021). The disorder shows overlapping features with autoimmune lymphoproliferative syndrome (ALPS); for a general description and a discussion of genetic heterogeneity of ALPS, see 601859.

Smith-Kingsmore syndrome (SKS) is a rare autosomal dominant syndromic intellectual disability syndrome characterized by macrocephaly, seizures, umbilical hernia, and facial dysmorphic features including frontal bossing, midface hypoplasia, small chin, hypertelorism with downslanting palpebral fissures, depressed nasal bridge, smooth philtrum, and thin upper lip (Smith et al., 2013; Baynam et al., 2015).

Immunodeficiency-44 (IMD44) is an autosomal recessive primary immunodeficiency characterized by increased susceptibility to viral infections and adverse multisystemic reaction to vaccination in some patients. Affected individuals appear to have defects in mitochondrial fission and fusion (summary by Shahni et al., 2015).

Individuals with Okur-Chung neurodevelopmental syndrome (OCNDS) frequently have nonspecific clinical features, delayed language development, motor delay, intellectual disability (typically in the mild-to-moderate range), generalized hypotonia starting in infancy, difficulty feeding, and nonspecific dysmorphic facial features. Developmental delay affects all areas of development, but language is more impaired than gross motor skills in most individuals. Intellectual disability has been reported in about three quarters of individuals. Less common findings may include kyphoscoliosis, postnatal short stature, disrupted circadian rhythm leading to sleep disturbance, seizures, and poor coordination.

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).

IMDDHH is a multisystem disorder characterized by immunodeficiency, mildly delayed psychomotor development, poor overall growth from infancy, and hypohomocysteinemia. Additional features, such as congenital heart defects and liver involvement, are more variable (summary by Huppke et al., 2017).

Immunodeficiency, centromeric instability, and facial dysmorphism (ICF) syndrome is a rare autosomal recessive disease characterized by facial dysmorphism, immunoglobulin deficiency, and branching of chromosomes 1, 9, and 16 after phytohemagglutinin (PHA) stimulation of lymphocytes. Hypomethylation of DNA of a small fraction of the genome is an unusual feature of ICF patients that is explained by mutations in the DNMT3B gene in some, but not all, ICF patients (Hagleitner et al., 2008). Genetic Heterogeneity of Immunodeficiency-Centromeric Instability-Facial Anomalies Syndrome See also ICF2 (614069), caused by mutation in the ZBTB24 gene (614064) on chromosome 6q21; ICF3 (616910), caused by mutation in the CDCA7 gene (609937) on chromosome 2q31; and ICF4 (616911), caused by mutation in the HELLS gene (603946) on chromosome 10q23.

B-cell expansion with NFKB and T-cell anergy is an autosomal dominant disorder characterized by onset in infancy of splenomegaly and polyclonal expansion of B cells, resulting in peripheral lymphocytosis. Affected individuals also show mild immune dysfunction, including some defective antibody responses and T-cell anergy. There may be a predisposition to the development of B-cell malignancy (summary by Snow et al., 2012).

Hyper-IgE syndrome-3 with recurrent infections (HIES3) is an autosomal recessive immunologic disorder characterized by childhood onset of atopic dermatitis, skin infections particularly with Staphylococcus aureus, recurrent sinopulmonary infections, and increased serum IgE and IgG. Patients are susceptible to bacterial and fungal infections, including chronic mucocutaneous candidiasis. Immunologic workup shows impaired differentiation of CD4+ T cells into T-helper 17 cells, decreased memory B cells, and often decreased NK cells (summary by Beziat et al., 2018). For a discussion of genetic heterogeneity of hyper-IgE syndrome, see HIES1 (147060).

Immunodeficiency-60 and autoimmunity (IMD60) is an autosomal dominant primary immunologic disorder characterized by inflammatory bowel disease and recurrent sinopulmonary infections. The age at symptom onset is highly variable, ranging from infancy to mid-adulthood. Laboratory studies show dysregulation of both B and T cells, with variably decreased immunoglobulin production, decreased T-regulatory cells, and overall impaired lymphocyte maturation (summary by Afzali et al., 2017).

Autosomal recessive primary immunodeficiency-14B (IMD14B) is characterized by onset of recurrent infections in early childhood. Most patients have respiratory infections, but some may develop inflammatory bowel disease or osteomyelitis. Laboratory studies tend to show hypogammaglobulinemia and decreased levels of B cells. Although NK cell and T cell numbers are normal, there may be evidence of impaired immune-mediated cytotoxicity and defective T-cell function (summary by et al., 2018 and et al., 2019).

VISS syndrome is a generalized connective tissue disorder characterized by early-onset thoracic aortic aneurysm and other connective tissue findings, such as aneurysm and tortuosity of other arteries, joint hypermobility, skin laxity, and hernias, as well as craniofacial dysmorphic features, structural cardiac defects, skeletal anomalies, and motor developmental delay (Van Gucht et al., 2021). Immune dysregulation has been observed in some patients (Ziegler et al., 2021).

Immunodeficiency-85 and autoimmunity (IMD85) is an autosomal dominant immunologic disorder characterized by onset of atopic eczema and recurrent respiratory infections in the first decade of life. Affected individuals also develop autoimmune enteropathy with vomiting, diarrhea, and poor overall growth. More variable features may include autoimmune oligoarthritis, interstitial pneumonitis, and EBV viremia. Laboratory studies show hypogammaglobulinemia and abnormal T-cell function, consistent with a combined immunodeficiency (Keskitalo et al., 2019).

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).

Immunodeficiency-102 (IMD102) is an X-linked recessive immunologic disorder characterized by the onset of recurrent sinopulmonary, mucosal, and other infections in early childhood, usually accompanied by refractory autoimmune cytopenias. Affected individuals have bacterial, viral, and fungal infections, as well as hemolytic anemia, thrombocytopenia, lymphopenia, and decreased NK cells. Laboratory studies show defective T-cell proliferation and function, likely due to signaling abnormalities. The disorder may also manifest as a hyperinflammatory state with immune dysregulation (Delmonte et al., 2021).

Autosomal dominant agammaglobulinemia-10 (AGM10) is characterized by early-childhood onset of recurrent viral and bacterial infections affecting various organ systems, particularly the sinopulmonary system. Laboratory studies show low or absent circulating B cells and hypo- or agammaglobulinemia. Affected individuals may have adverse reactions to certain vaccinations, such as the polio vaccine. Treatment with replacement Ig is effective; hematopoietic stem cell transplantation has also been reported (summary by Le Coz et al., 2021). For a discussion of genetic heterogeneity of autosomal agammaglobulinemia, see AGM1 (601495).

Hyper-IgE syndrome-4A with recurrent infections (HIES4A) is an autosomal dominant immunologic disorder characterized by recurrent, mainly sinopulmonary infections associated with increased serum IgE. The phenotype is variable, even within families. Some patients have onset of symptoms in early childhood and develop complications, including bronchiectasis or hemoptysis, whereas others have later onset of less severe infections. Immunologic workup usually shows normal leukocyte levels, although some patients may demonstrate alterations in lymphocyte subsets, including T cells. Affected individuals also have variable skeletal abnormalities, including high-arched palate, hyperextensible joints, scoliosis, and bone fractures. The IL6ST mutations are loss-of-function, although the truncated mutant proteins are expressed and interfere with the wildtype protein in a dominant-negative manner by disrupting IL6 (147620) and IL11 (147681) signaling (summary by Beziat et al., 2020). For a discussion of genetic heterogeneity of hyper-IgE syndrome, see HIES1 (147060).

Immunodeficiency-96 (IMD96) is an autosomal recessive disorder characterized by onset of recurrent, usually viral, respiratory infections in infancy or early childhood. Other infections, including gastrointestinal and urinary tract infections, may also occur. Laboratory studies show hypogammaglobulinemia, lymphopenia with increased gamma/delta T cells, and erythrocyte macrocytosis. The disorder results from defective cellular DNA repair (summary by Maffucci et al., 2018).

Immunodeficiency-97 with autoinflammation (IMD97) is an autosomal recessive complex immunologic disorder with variable features. Affected individuals present in the first decade of life with inflammatory interstitial lung disease or colitis due to abnormal tissue infiltration by activated T cells. Patients develop autoimmune cytopenias and may have lymphadenopathy; 1 reported patient had features of hemophagocytic lymphohistiocytosis (HLH; see FHL1, 267700). Some patients may have recurrent infections associated with mild lymphopenia, hypogammaglobulinemia, and NK cell dysfunction. Immunologic workup indicates signs of significant immune dysregulation with elevation of inflammatory serum markers, variable immune cell defects involving neutrophils, NK cells, and myeloid cells, and disrupted levels of T regulatory cells (Tregs). Two unrelated patients have been reported (summary by Takeda et al., 2019 and Thian et al., 2020).

Autosomal recessive agammaglobulinemia-8B (AGM8B) is characterized by onset of recurrent infections in early childhood. Laboratory studies of affected individuals show decreased circulating immunoglobulins and decreased peripheral B cells. More variable features may include dysmorphic facies and subtle abnormalities of other immune cells, such as T cells. One patient who developed childhood B-cell acute lymphocytic leukemia (B-ALL) has been described (summary by Ben-Ali et al., 2017).

Immunodeficiency-105 (IMD105) is an autosomal recessive disorder characterized by onset of recurrent infections in early infancy. Manifestations may include pneumonia, dermatitis, and lymphadenopathy. B-cell lymphoma was reported in 1 patient. Laboratory studies show decreased or absent numbers of nonfunctional T cells, normal or increased levels of B cells, hypogammaglobulinemia, and normal or low NK cells. The disorder is caused by a deficiency of transmembrane protein CD45 (PTPRC) on leukocytes, which plays an important role in T- and B-cell development (Cale et al., 1997; Kung et al., 2000). For a general phenotypic description and a discussion of genetic heterogeneity of autosomal recessive SCID, see 601457.

Primordial dwarfism-immunodeficiency-lipodystrophy syndrome (PDIL) is characterized by pre- and postnatal growth restriction, with extreme microcephaly, short stature, and absence of subcutaneous fat. There is also significant hematologic/immune dysfunction, with hypo- or agammaglobulinemia, as well as lymphopenia, anemia, and thrombocytopenia, and most affected individuals succumb to infection in early childhood (Parry et al., 2020).

Digenic dyskeratosis congenita (DKCD) is characterized clinically by a combination of mucocutaneous features including abnormal skin pigmentation, nail dystrophy, thin hair, and oral leukoplakia. Some patients may have evidence of bone marrow failure, manifest as immune defects such as recurrent infections or hypogammaglobulinemia. Telomeres are shortened in patient cells. Individuals with DKCD may show severe adverse reactions to treatment with 5-FU (Tummala et al., 2022). For a discussion of genetic heterogeneity of dyskeratosis congenita, see DKCA1 (127550).