Alpha-mannosidosis encompasses a continuum of clinical findings from mild to severe. Three major clinical subtypes have been suggested: A mild form recognized after age ten years with absence of skeletal abnormalities, myopathy, and slow progression (type 1). A moderate form recognized before age ten years with presence of skeletal abnormalities, myopathy, and slow progression (type 2). A severe form manifested as prenatal loss or early death from progressive central nervous system involvement or infection (type 3). Individuals with a milder phenotype have mild-to-moderate intellectual disability, impaired hearing, characteristic coarse features, clinical or radiographic skeletal abnormalities, immunodeficiency, and primary central nervous system disease – mainly cerebellar involvement causing ataxia. Periods of psychiatric symptoms are common. Associated medical problems can include corneal opacities, hepatosplenomegaly, aseptic destructive arthritis, and metabolic myopathy. Alpha-mannosidosis is insidiously progressive; some individuals may live into the sixth decade.

Complement hyperactivation, angiopathic thrombosis, and protein-losing enteropathy (CHAPLE) is characterized by abdominal pain and diarrhea, primary intestinal lymphangiectasia, hypoproteinemic edema, and malabsorption. Some patients also exhibit bowel inflammation, recurrent infections associated with hypogammaglobulinemia, and/or angiopathic thromboembolic disease. Patient T lymphocytes show increased complement activation, causing surface deposition of complement and generating soluble C5a (Ozen et al., 2017).

Thrombocytopenia absent radius (TAR) syndrome is characterized by bilateral absence of the radii with the presence of both thumbs, and thrombocytopenia that is generally transient. Thrombocytopenia may be congenital or may develop within the first few weeks to months of life; in general, thrombocytopenic episodes decrease with age. Cow's milk allergy is common and can be associated with exacerbation of thrombocytopenia. Other anomalies of the skeleton (upper and lower limbs, ribs, and vertebrae), heart, and genitourinary system (renal anomalies and agenesis of uterus, cervix, and upper part of the vagina) can occur.

Schimke immunoosseous dysplasia (SIOD) is characterized by spondyloepiphyseal dysplasia (SED) resulting in short stature, nephropathy, and T-cell deficiency. Radiographic manifestations of SED include ovoid and mildly flattened vertebral bodies, small ilia with shallow dysplastic acetabular fossae, and small deformed capital femoral epiphyses. Nearly all affected individuals have progressive steroid-resistant nephropathy, usually developing within five years of the diagnosis of growth failure and terminating with end-stage renal disease. The majority of tested individuals have T-cell deficiency and an associated risk for opportunistic infection, a common cause of death. SIOD involves a spectrum that ranges from an infantile or severe early-onset form with a greater risk of death during childhood to a juvenile or milder later-onset form with likely survival into adulthood if renal disease is appropriately treated.

X-linked lymphoproliferative disease (XLP) has two recognizable subtypes, XLP1 and XLP2. XLP1 is characterized predominantly by one of three commonly recognized phenotypes: Inappropriate immune response to Epstein-Barr virus (EBV) infection leading to hemophagocytic lymphohistiocytosis (HLH) or severe mononucleosis. Dysgammaglobulinemia. Lymphoproliferative disease (malignant lymphoma). XLP2 is most often characterized by HLH (often associated with EBV), dysgammaglobulinemia, and inflammatory bowel disease. HLH resulting from EBV infection is associated with an unregulated and exaggerated immune response with widespread proliferation of cytotoxic T cells, EBV-infected B cells, and macrophages. Dysgammaglobulinemia is typically hypogammaglobulinemia of one or more immunoglobulin subclasses. The malignant lymphomas are typically B-cell lymphomas, non-Hodgkin type, often extranodal, and in particular involving the intestine.

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).

Macrocephaly/autism syndrome is an autosomal dominant disorder characterized by increased head circumference, abnormal facial features, and delayed psychomotor development resulting in autistic behavior or mental retardation (Herman et al., 2007). Some patients may have a primary immunodeficiency disorder with recurrent infections associated with variably abnormal T- and B-cell function (Tsujita et al., 2016).

Immunodeficiency-59 and hypoglycemia (IMD59) is an autosomal recessive primary immunologic disorder characterized by combined immunodeficiency and recurrent septic infections of the respiratory tract, skin, and mucous membranes, as well as disturbed glucose metabolism. Granulocytopenia and B-cell and dendritic cell deficiency are present (Haapaniemi et al., 2017).

Wolfram syndrome-2 (WFS2) is an autosomal recessive neurodegenerative disorder characterized by diabetes mellitus, high frequency sensorineural hearing loss, optic atrophy or neuropathy, and defective platelet aggregation resulting in peptic ulcer bleeding (summary by Mozzillo et al., 2014). For a discussion of genetic heterogeneity of Wolfram syndrome, see WFS1 (222300).

Familial hemophagocytic lymphohistiocytosis-5 with or without microvillus inclusion disease (FHL5) is an autosomal recessive hyperinflammatory disorder characterized clinically by fever, hepatosplenomegaly, pancytopenia, coagulation abnormalities, and other laboratory findings. Some patients have neurologic symptoms due to inflammatory CNS disease. There is uncontrolled and ineffective proliferation and activation of T lymphocytes, NK cells, and macrophages that infiltrate multiple organs, including liver, spleen, lymph nodes, and the CNS. The phenotype is variable: some patients may present in early infancy with severe diarrhea, prior to the onset of typical FHL features, whereas others present later in childhood and have a more protracted course without diarrhea. The early-onset diarrhea is due to enteropathy reminiscent of microvillus inclusion disease (see MVID, 251850). The enteropathy, which often necessitates parenteral feeding, may be the most life-threatening issue even after hematopoietic stem cell transplantation (HSCT). More variable features include sensorineural hearing loss and hypogammaglobulinemia. Treatment with immunosuppressive drugs and chemotherapy can ameliorate signs and symptoms of FHL in some patients, but the only curative therapy for FHL is HSCT. HSCT is not curative for enteropathy associated with the disorder, despite hematologic and immunologic reconstitution (summary by Meeths et al., 2010; Pagel et al., 2012; Stepensky et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of familial hemophagocytic lymphohistiocytosis (FHL, HLH), see 267700.

Nijmegen breakage syndrome-like disorder (NBSLD) is an autosomal recessive disorder characterized by severe prenatal growth retardation and persistent postnatal growth restriction, congenital microcephaly, borderline to mildly impaired intellectual development, normal sexual development, and radioresistant DNA synthesis with no immunodeficiency, myelodysplasia, or early neurodegeneration (summary by Ragamin et al., 2020).

Agammaglobulinemia is a primary immunodeficiency characterized by profoundly low or absent serum antibodies and low or absent circulating B cells due to an early block of B-cell development. Affected individuals develop severe infections in the first years of life. The most common form of agammaglobulinemia is X-linked agammaglobulinemia (AGMX1, XLA; 300755), also known as Bruton disease, which is caused by mutation in the BTK gene (300300). AGMX1 accounts for anywhere from 85 to 95% of males who have the characteristic findings (Lopez Granados et al., 2002; Ferrari et al., 2007). Autosomal recessive inheritance of agammaglobulinemia, which has a similar phenotype to that of the X-linked form, has been observed in a small number of families, and accounts for up to 15% of patients with agammaglobulinemia (Ferrari et al., 2007). Conley (1999) gave a comprehensive review of autosomal recessive agammaglobulinemia. Genetic Heterogeneity of Autosomal Agammaglobulinemia Autosomal agammaglobulinemia is a genetically heterogeneous disorder: see also AGM2 (613500), caused by mutation in the IGLL1 gene (146770); AGM3 (613501), caused by mutation in the CD79A gene (112205); AGM4 (613502), caused by mutation in the BLNK gene (604515); AGM5 (613506), caused by disruption of the LRRC8 gene (608360); AGM6 (612692), caused by mutation in the CD79B gene (147245); AGM7 (615214), caused by mutation in the PIK3R1 gene (171833); AGM8 (616941), caused by mutation in the TCF3 gene (147141); AGM9 (619693), caused by mutation in the SLC39A7 gene (601416); and AGM10 (619707), caused by mutation in the SPI1 gene (165170).

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).

Lymphoproliferative syndrome-1 is an autosomal recessive primary immunodeficiency characterized by onset in early childhood of Epstein-Barr virus (EBV)-associated immune dysregulation, manifest as lymphoma, lymphomatoid granulomatosis, hemophagocytic lymphohistiocytosis, Hodgkin disease, and/or hypogammaglobulinemia. Autoimmune disorders, such as autoimmune hemolytic anemia or renal disease, may also occur. Patients show a high EBV viral load and decreased invariant natural killer T cells. It is unknown whether patients with ITK mutations are intrinsically susceptible to development of lymphoma or dysgammaglobulinemia in the absence of EBV infection (summary by Stepensky et al., 2011; Linka et al., 2012). For a discussion of genetic heterogeneity of lymphoproliferative syndrome, see XLP1 (308240).

Lymphoproliferative syndrome-2, also known as CD27 deficiency, is an autosomal recessive immunodeficiency disorder associated with persistent symptomatic EBV viremia, hypogammaglobulinemia, and impairment in specific antibody function resulting from impaired T cell-dependent B-cell responses and T-cell dysfunction (summary by van Montfrans et al., 2012). The phenotype can vary significantly, from asymptomatic borderline-low hypogammaglobulinemia, to a full-blown symptomatic systemic inflammatory response with life-threatening EBV-related complications, including hemophagocytic lymphohistiocytosis, a lymphoproliferative disorder, and malignant lymphoma requiring stem cell transplantation (summary by Salzer et al., 2013). For a discussion of genetic heterogeneity of lymphoproliferative syndrome, see XLP1 (308240).

Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.

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).

Adenosine deaminase 2 deficiency (DADA2) is a complex systemic autoinflammatory disorder in which vasculopathy/vasculitis, dysregulated immune function, and/or hematologic abnormalities may predominate. Inflammatory features include intermittent fevers, rash (often livedo racemosa/reticularis), and musculoskeletal involvement (myalgia/arthralgia, arthritis, myositis). Vasculitis, which usually begins before age ten years, may manifest as early-onset ischemic (lacunar) and/or hemorrhagic strokes, or as cutaneous or systemic polyarteritis nodosa. Hypertension and hepatosplenomegaly are often found. More severe involvement may lead to progressive central neurologic deficits (dysarthria, ataxia, cranial nerve palsies, cognitive impairment) or to ischemic injury to the kidney, intestine, and/or digits. Dysregulation of immune function can lead to immunodeficiency or autoimmunity of varying severity; lymphadenopathy may be present and some affected individuals have had lymphoproliferative disease. Hematologic disorders may begin early in life or in late adulthood, and can include lymphopenia, neutropenia, pure red cell aplasia, thrombocytopenia, or pancytopenia. Of note, both interfamilial and intrafamilial phenotypic variability (e.g., in age of onset, frequency and severity of manifestations) can be observed; also, individuals with biallelic ADA2 pathogenic variants may remain asymptomatic until adulthood or may never develop clinical manifestations of DADA2.

Primary ciliary dyskinesia-29 is an autosomal recessive disorder characterized by early childhood onset of recurrent respiratory infections due to defective mucociliary clearance. Patients do not have situs inversus (summary by Wallmeier et al., 2014). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see 244400.

Infantile-onset multisystem autoimmune disease-1 is characterized by early childhood onset of a spectrum of autoimmune disorders affecting multiple organs. Common manifestations include insulin-dependent diabetes mellitus and autoimmune enteropathy, or celiac disease, and autoimmune hematologic disorders. Other features include short stature and nonspecific dermatitis. More variable features include hypothyroidism, autoimmune arthritis, and delayed puberty. Some patients may show recurrent infections. The disorder results from an inborn error of cytokine signaling (summary by Flanagan et al., 2014 and Milner et al., 2015). Genetic Heterogeneity of Infantile-Onset Multisystem Autoimmune Disease See also ADMIO2 (617006), caused by mutation in the ZAP70 gene (176947) on chromosome 2q12, and ADMIO3 (620430), caused by mutation in the CBLB gene (604491) on chromosome 3q13.

Sideroblastic anemia with B-cell immunodeficiency, periodic fevers, and developmental delay (SIFD) is an autosomal recessive syndromic disorder characterized by onset of severe sideroblastic anemia in the neonatal period or infancy. Affected individuals show delayed psychomotor development with variable neurodegeneration. Recurrent periodic fevers without an infectious etiology occur throughout infancy and childhood; immunologic work-up shows B-cell lymphopenia and hypogammaglobulinemia. Other more variable features include sensorineural hearing loss, retinitis pigmentosa, nephrocalcinosis, and cardiomyopathy. Death in the first decade may occur (summary by Wiseman et al., 2013).

Any primary immunodeficiency disease in which the cause of the disease is a mutation in the BCL10 gene.

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.

Common variable immunodeficiency-13 (CVID13) is an autosomal dominant primary immunodeficiency disorder characterized by recurrent bacterial infections, mainly affecting the respiratory tract, and associated with hypogammaglobulinemia and decreased numbers of B cells. The age at onset of clinical features can range from infancy to adulthood, and some patients may have a mild disorder or even remain clinically asymptomatic (summary by Kuehn et al., 2016). For a general description and a discussion of genetic heterogeneity of common variable immunodeficiency, see CVID1 (607594).

Common variable immunodeficiency-12 with autoimmunity (CVID12) is an autosomal dominant complex immunologic disorder with multisystem involvement. CVID12 is mainly a primary immunodeficiency characterized by recurrent infections and associated with hypogammaglobulinemia. Notably, about half of patients develop autoimmune features, including cytopenia, as well as generalized inflammation and lymphoproliferation manifest as lymphadenopathy or hepatosplenomegaly. A smaller percentage of affected individuals (less than 20%) develop cancer, most commonly solid tumors, including lymphoma. Age at onset and disease severity are highly variable, even within the same family. There is also incomplete penetrance, such that mutation carriers may be asymptomatic, even if they have hypogammaglobulinemia. The gene involved, NFKB1, encodes a transcription factor that regulates the expression of target genes involved in the immune system, thus defining the phenotype as a disorder of immune dysregulation (summary by Fliegauf et al., 2015; Lorenzini et al., 2020). For a general description and a discussion of genetic heterogeneity of common variable immunodeficiency, see CVID1 (607594).

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.

Immunodeficiency-centromeric instability-facial anomalies syndrome-4 is an autosomal recessive disorder characterized by recurrent infections in childhood and variable dysmorphic facial features. Laboratory studies show hypomethylation of certain chromosomal regions. Additional features, including delayed development, are variable (summary by Thijssen et al., 2015). For a discussion of genetic heterogeneity of immunodeficiency-centromeric instability-facial anomalies syndrome, see ICF1 (242860).

Immunodeficiency-centromeric instability-facial anomalies syndrome-3 is an autosomal recessive disorder characterized by recurrent infections in childhood and variable dysmorphic facial features. Laboratory studies show hypomethylation of certain chromosomal regions. Additional features, including delayed development, are variable (summary by Thijssen et al., 2015). For a discussion of genetic heterogeneity of immunodeficiency-centromeric instability-facial anomalies syndrome, see ICF1 (242860).

Immunodeficiency-47 (IMD47) is an X-linked recessive complex syndrome characterized by liver dysfunction, recurrent bacterial infections, hypogammaglobulinemia, and defective glycosylation of serum proteins. Some patients also have neurologic abnormalities (summary by Jansen 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).

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).

Combined immunodeficiency and megaloblastic anemia with or without hyperhomocysteinemia is an inborn error of folate metabolism due to deficiency of methylenetetrahydrofolate dehydrogenase-1. Manifestations may include hemolytic uremic syndrome, macrocytosis, epilepsy, hearing loss, retinopathy, mild mental retardation, lymphopenia involving all subsets, and low T-cell receptor excision circles. Folinic acid supplementation is an effective treatment (summary by Ramakrishnan et al., 2016).

Trichohepatoenteric syndrome (THES), generally considered to be a neonatal enteropathy, is characterized by intractable diarrhea (seen in almost all affected children), woolly hair (seen in all), intrauterine growth restriction, facial dysmorphism, and short stature. Additional findings include poorly characterized immunodeficiency, recurrent infections, skin abnormalities, and liver disease. Mild intellectual disability (ID) is seen in about 50% of affected individuals. Less common findings include congenital heart defects and platelet anomalies. To date 52 affected individuals have been reported.

Immunodeficiency-15B (IMD15B) is an autosomal recessive primary immunodeficiency disorder characterized by onset in infancy of life-threatening bacterial, fungal, and viral infections and failure to thrive. Laboratory studies show hypo- or agammaglobulinemia with relatively normal numbers of B and T cells. However, functional studies show impaired differentiation and activation of immune cells (summary by Pannicke et al., 2013).

Immunodeficiency-100 with pulmonary alveolar proteinosis and hypogammaglobulinemia (IMD100) is primarily a lung disorder characterized by onset of respiratory insufficiency due to pulmonary alveolar proteinosis (PAP) in the first months of life. Affected individuals may have normal respiratory function at birth. Development of the disorder appears to be influenced or triggered by viral infection, manifest as progressive respiratory insufficiency, confluent consolidations on lung imaging, and diffuse collection of periodic acid-Schiff (PAS)-positive material in pulmonary alveoli associated with small and nonfoamy alveolar macrophages. Patients also have hypogammaglobulinemia, leukocytosis, and splenomegaly. Many patients die of respiratory failure in infancy or early childhood; hematopoietic stem cell transplantation (HSCT) is curative. The pathogenesis may be related to abnormal function of alveolar macrophages, resulting in decreased catabolism of surfactant (summary by Cho et al., 2018). Magg et al. (2021) determined that the disorder results from a gain-of-function effect that particularly affects B cells and monocytes.

BMFS4 is an autosomal recessive disorder characterized by early-onset anemia, leukopenia, and decreased B cells, resulting in the necessity for red cell transfusion and sometimes causing an increased susceptibility to infection. Some patients may have thrombocytopenia or variable additional nonhematologic features, such as facial dysmorphism, skeletal anomalies, and mild developmental delay. Bone marrow transplantation is curative (summary by Bahrami et al., 2017). For a discussion of genetic heterogeneity of BMFS, see BMFS1 (614675).

Immunodeficiency-58 is an autosomal recessive primary immunologic disorder characterized by early-onset skin lesions, including eczematous dermatitis, infectious abscesses, and warts, recurrent respiratory infections or allergies, and chronic persistent infections with candida, Molluscum contagiosum, mycobacteria, EBV, bacteria, and viruses. Some patients may have gastrointestinal involvement, including inflammatory bowel disease, EBV+ smooth muscle tumors, and esophagitis. Immunologic analysis shows defective T-cell function with decreased Treg cells and deficient CD3/CD28 costimulation responses in both CD4+ and CD8+ T cells. B-cell function may also be impaired (summary by Wang et al., 2016 and Alazami et al., 2018).

Bone marrow failure syndrome-5 (BMFS5) is a hematologic disorder characterized by infantile onset of severe red cell anemia requiring transfusion. Additional features include hypogammaglobulinemia, poor growth with microcephaly, developmental delay, and seizures (summary by Toki et al., 2018) For a discussion of genetic heterogeneity of BMFS, see BMFS1 (614675).

Diarrhea-10 (DIAR10) is a protein-losing enteropathy characterized by intractable secretory diarrhea and massive protein loss due to leaky fenestrated capillaries. Features include early-onset anasarca, severe hypoalbuminemia, hypogammaglobulinemia, and hypertriglyceridemia, as well as electrolyte abnormalities. Some patients exhibit facial dysmorphism and cardiac and renal anomalies. Intrafamilial variability has been observed, and the disease can be severe, with death occurring in infancy in some patients (Broekaert et al., 2018; Kurolap et al., 2018). For a discussion of genetic heterogeneity of diarrhea, see DIAR1 (214700).

Congenital disorder of glycosylation type 2R (CDG2R) is an X-linked recessive disorder characterized by infantile onset of liver failure, recurrent infections due to hypogammaglobulinemia, and cutis laxa. Some patients may also have mild intellectual impairment and dysmorphic features. Laboratory studies showed defective glycosylation of serum transferrin in a type 2 pattern (summary by Rujano et al., 2017). For an overview of congenital disorders of glycosylation, see CDG1A (212065) and CDG2A (212066).

X-linked lymphoproliferative disease (XLP) has two recognizable subtypes, XLP1 and XLP2. XLP1 is characterized predominantly by one of three commonly recognized phenotypes: Inappropriate immune response to Epstein-Barr virus (EBV) infection leading to hemophagocytic lymphohistiocytosis (HLH) or severe mononucleosis. Dysgammaglobulinemia. Lymphoproliferative disease (malignant lymphoma). XLP2 is most often characterized by HLH (often associated with EBV), dysgammaglobulinemia, and inflammatory bowel disease. HLH resulting from EBV infection is associated with an unregulated and exaggerated immune response with widespread proliferation of cytotoxic T cells, EBV-infected B cells, and macrophages. Dysgammaglobulinemia is typically hypogammaglobulinemia of one or more immunoglobulin subclasses. The malignant lymphomas are typically B-cell lymphomas, non-Hodgkin type, often extranodal, and in particular involving the intestine.

Immunodeficiency-70 (IMD70) is an autosomal dominant immunologic disorder characterized by severe cutaneous warts on the hands, feet, and face, suggesting increased susceptibility to human papillomavirus (HPV) infection. Affected individuals may also have recurrent bacterial infections, such as sinusitis, as well as feature of autoinflammation, such as colitis, celiac disease, and retinal vasculitis. Laboratory studies show decreased CD4+ T cells and decreased CD19+ B cells; hypogammaglobulinemia has also been observed (summary by Thaventhiran et al., 2020).

WHIM syndrome-1 (WHIMS1) is an autosomal dominant immunologic disorder characterized by neutropenia, hypogammaglobulinemia, and warts due to human papillomavirus (HPV) infection. Despite the peripheral neutropenia, bone marrow aspirates from affected individuals contain abundant mature myeloid cells, a condition termed myelokathexis. The susceptibility to HPV is disproportionate compared with other immunodeficiency conditions (summary by Hernandez et al., 2003). Heusinkveld et al. (2019) provided a detailed review of the clinical features, proposed pathogenesis, and possible therapeutic treatments of WHIM syndrome. There is significant phenotypic variation among patients, such that some individuals may have an 'incomplete' form of the disorder in which one or more of the classic tetrad features are not present. In general, the WHIMS phenotype comprises a spectrum of manifestations with variable expressivity. The pathogenesis of WHIMS1 is postulated to result from impaired CXCL12 (600835)-induced internalization of CXCR4, resulting in prolonged receptor presence at the cell surface that likely contributes to amplification of signaling with a gain-of-function effect. Genetic Heterogeneity of WHIM Syndrome See also WHIMS2 (619407), caused by mutation in the CXCR2 gene (146928) on chromosome 2q35.

IMD50 is an X-linked recessive primary immunodeficiency characterized by the onset of recurrent bacterial or varicella zoster virus (VZV) infections in early childhood. Laboratory studies show profound lymphopenia, hypogammaglobulinemia, poor immune response to vaccine antigens, and fluctuating neutropenia. The disorder does not affect overall patient survival (summary by Lagresle-Peyrou et al., 2016).

A rare genetic combined T and B cell immunodeficiency characterised by life-threatening infections due to disrupted transferrin receptor 1 endocytosis, resulting in defective cellular iron transport and impaired T and B cell function. Patients present with early-onset chronic diarrhoea, severe recurrent infections and failure to thrive. Laboratory studies reveal hypo or agammaglobulinaemia, normal lymphocyte counts but decreased numbers of memory B cells, intermittent neutropenia and thrombocytopenia, and mild anaemia (resistant to iron supplementation) with low mean corpuscular volume.

Lymphoproliferative syndrome-3 (LPFS3) is an autosomal recessive early-onset immunologic disorder characterized by increased susceptibility to Epstein-Barr virus (EBV) infection in B cells, resulting in abnormal B-cell proliferation and increased susceptibility to B-cell malignancies, including Hodgkin lymphoma. Patients usually have hypogammaglobulinemia without lymphopenia, although some subsets of immune cells may be low and some patients may have recurrent infections. The disorder results from impaired signaling from proliferating B cells to effector T cells that provide immune surveillance. There may be an increased risk of solid tumors in heterozygous carriers (summary by Abolhassani et al., 2017). For a discussion of genetic heterogeneity of lymphoproliferative syndrome, see XLP1 (308240).

X-linked systemic autoinflammatory disease (SAIDX) is characterized by the onset of systemic autoinflammation in the first months of life. Features include lymphadenopathy, hepatosplenomegaly, fever, panniculitis, and nodular skin rash. Additional manifestations may include inflammation of the optic nerve, intracranial hemorrhage, and lipodystrophy. Laboratory studies show hypogammaglobulinemia, increased or decreased white blood cell count, autoimmune cytopenias, elevated serum inflammatory markers, and a type I interferon signature (de Jesus et al., 2020 and Lee et al., 2022).

Immunodeficiency-94 with autoinflammation and dysmorphic facies (IMD94) is a systemic immunologic disorder with onset in early infancy. Primary features include lymphadenopathy, autoinflammation, immunodeficiency with hypogammaglobulinemia, and dysmorphic facial features. Intellectual development is normal and serum IgE is not elevated. The disease results from constitutive activation of the IL6 signaling cascade, resulting in immune dysregulation and a hyperinflammatory state (summary by Materna-Kiryluk et al., 2021).

Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF.

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).

Immunodeficiency-99 with hypogammaglobulinemia and autoimmune cytopenias (IMD99) is an autosomal recessive immunologic disorder characterized by the onset of recurrent sinopulmonary infections in early childhood. Laboratory studies reveal hypogammaglobulinemia with decreased memory B cells that show impaired class-switch recombination (CSR) and decreased somatic hypermutation (SHM). Due to abnormal antibody production and impaired self-tolerance, patients may develop autoimmune cytopenias, such as thrombocytopenia, or autoimmune features, such as vitiligo. There are also defects in the T-cell compartment (Kuhny et al., 2020).

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.

Gastrointestinal defects and immunodeficiency syndrome-1 (GIDID1) is characterized by multiple intestinal atresia, in which atresia occurs at various levels throughout the small and large intestines. Surgical outcomes are poor, and the condition is usually fatal within the first month of life. Some patients exhibit inflammatory bowel disease (IBD), with or without intestinal atresia, and in some cases, the intestinal features are associated with either mild or severe combined immunodeficiency (Samuels et al., 2013; Avitzur et al., 2014; Lemoine et al., 2014). Genetic Heterogeneity of GIDID See also GIDID2 (619708), caused by mutation in the PI4KA gene (600286) on chromosome 22q11.