The phenotypic spectrum of ataxia-telangiectasia (A-T), a multisystem disorder, is a continuum ranging from classic A-T at the severe end and variant A-T at the milder end. Nonetheless, distinguishing between classic A-T and variant A-T on this spectrum helps understand differences in disease course, rate of progression, and life expectancy. Classic A-T is characterized by childhood onset of progressive neurologic manifestations (initially cerebellar ataxia, followed typically by extrapyramidal involvement and peripheral sensorimotor neuropathy), immunodeficiency (variably associated with abnormalities of humoral immunity, cellular immunity, or combined immune deficiency), pulmonary disease (resulting from recurrent infections, immune deficiency, aspiration, interstitial lung disease, and neurologic abnormalities), and increased risk of malignancy. Although it is generally accepted that intellectual disability is not common in A-T, disturbances in cerebellar as well as non-cerebellar brain areas and networks may result in cognitive deficits. Increased sensitivity to ionizing radiation (x-ray and gamma ray) can result in severe side effects from such treatments. Life expectancy is significantly reduced due to cancer, pulmonary disease, and infections. Variant A-T has a significantly milder disease course. While cerebellar ataxia can be absent, extrapyramidal movement disorders are common (typically dystonia and dystonic tremor) and most individuals have manifestations of axonal sensorimotor polyneuropathy. In contrast to classic A-T, immune function is generally normal, respiratory infections are not increased, and pulmonary disease is not a major feature. However, risk of developing malignancies is increased, particularly in premenopausal females who have an increased risk of developing breast cancer and hematologic malignancies.

T-cell immunodeficiency with thymic aplasia (TIDTA) is an autosomal recessive disorder that is often detected at birth through newborn SCID screening with the finding of decreased T-cell receptor excision circles (TRECs). Affected individuals have selective hypo- or aplasia of the thymus, which results in T-cell immunodeficiency due to impaired T-cell development and increased susceptibility to viral infections. The phenotype is similar to T-/B+/NK+ SCID. Some patients may die in childhood; thymus transplantation may be curative (summary by Du et al., 2019).

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 manifesting 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 immunoglobulin G to be achieved, and more liberal use of antibiotics.

Nijmegen breakage syndrome (NBS) is characterized by progressive microcephaly, early growth deficiency that improves with age, recurrent respiratory infections, an increased risk for malignancy (primarily lymphoma), and premature ovarian failure in females. Developmental milestones are attained at the usual time during the first year; however, borderline delays in development and hyperactivity may be observed in early childhood. Intellectual abilities tend to decline over time. Recurrent pneumonia and bronchitis may result in respiratory failure and early death. Other reported malignancies include solid tumors (e.g., medulloblastoma, glioma, rhabdomyosarcoma).

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.

Severe combined immunodeficiency refers to a genetically and clinically heterogeneous group of disorders with defective cellular and humoral immune function. Patients with SCID present in infancy with recurrent, persistent infections by opportunistic organisms, including Candida albicans, Pneumocystis carinii, and cytomegalovirus, among many others. Laboratory analysis shows profound lymphopenia with diminished or absent immunoglobulins. The common characteristic of all types of SCID is absence of T cell-mediated cellular immunity due to a defect in T-cell development. Without treatment, patients usually die within the first year of life. The overall prevalence of all types of SCID is approximately 1 in 75,000 births (Fischer et al., 1997; Buckley, 2004). Genetic Heterogeneity of SCID SCID can be divided into 2 main classes: those with B lymphocytes (B+ SCID) and those without (B- SCID). Presence or absence of NK cells is variable within these groups. The most common form of SCID is X-linked T-, B+, NK- SCID (SCIDX1; 300400) caused by mutation in the IL2RG gene (308380) on chromosome Xq13.1. Autosomal recessive SCID includes T-, B-, NK+ SCID, caused by mutation in the RAG1 and RAG2 genes on 11p13; T-, B+, NK- SCID (600802), caused by mutation in the JAK3 gene (600173) on 19p13; T-, B+, NK+ SCID (IMD104; 608971), caused by mutation in the IL7R gene (146661) on 5p13; T-, B+, NK+ SCID (IMD105; 619924), caused by mutation in the CD45 gene (PTPRC; 151460) on 1q31-q32; T-, B+, NK+ SCID (IMD19; 615617), caused by mutation in the CD3D gene (186790) on 11q23; T-, B-, NK- SCID (102700) caused by mutation in the ADA (608958) gene on 20q13; and T-, B-, NK+ SCID with sensitivity to ionizing radiation (602450), caused by mutation in the Artemis gene (DCLRE1C; 605988) on 10p13 (Kalman et al., 2004); T-, B+, NK+ SCID with intellectual disability, spasticity, and craniofacial abnormalities (IMD49; 617237), caused by mutation in the BCL11B gene (606558) on 14q32; and T-, B-, NK+ SCID with microcephaly, growth retardation, and sensitivity to ionizing radiation (IMD124; 611291), caused by mutation in the NHEJ1 gene (611290) on 2q35. Approximately 20 to 30% of all SCID patients are T-, B-, NK+, and approximately half of these patients have mutations in the RAG1 or RAG2 genes (Schwarz et al., 1996; Fischer et al., 1997).

JAK3-deficient severe combined immunodeficiency (SCID) is an inherited disorder of the immune system. Individuals with JAK3-deficient SCID lack the necessary immune cells to fight off certain bacteria, viruses, and fungi. They are prone to repeated and persistent infections that can be very serious or life-threatening. Often the organisms that cause infection in people with JAK3-deficient SCID are described as opportunistic because they ordinarily do not cause illness in healthy people. Affected infants typically develop chronic diarrhea, a fungal infection in the mouth called oral thrush, pneumonia, and skin rashes. Persistent illness also causes affected individuals to grow more slowly than other children. Without treatment, people with JAK3-deficient SCID usually live only into early childhood.

Spondyloenchondrodysplasia with immune dysregulation (SPENCDI) is an immunoosseous dysplasia combining the typical metaphyseal and vertebral bone lesions of spondyloenchondrodysplasia (SPENCD) with immune dysfunction and neurologic involvement. The skeletal dysplasia is characterized by radiolucent and irregular spondylar and metaphyseal lesions that represent islands of chondroid tissue within bone. The vertebral bodies show dorsally accentuated platyspondyly with disturbance of ossification. Clinical abnormalities such as short stature, rhizomelic micromelia, increased lumbar lordosis, barrel chest, facial anomalies, and clumsy movements may be present (Menger et al., 1989). Central nervous system involvement includes spasticity, mental retardation, and cerebral calcifications, and immune dysregulation ranges from autoimmunity to immunodeficiency. Neurologic and autoimmune manifestations have been observed in different combinations within a single family, suggesting that this disorder may be defined by specific radiographic features but has remarkably pleiotropic manifestations (Renella et al., 2006). Briggs et al. (2016) also noted variability in skeletal, neurologic, and immune phenotypes, which was sometimes marked between members of the same family. Classification of the Enchondromatoses In their classification of the enchondromatoses, Spranger et al. (1978) called Ollier disease and Maffucci syndrome types I and II enchondromatosis, respectively; metachondromatosis (156250), type III; and spondyloenchondrodysplasia (SPENCD), also called spondyloenchondromatosis, type IV; enchondromatosis with irregular vertebral lesions, type V; and generalized enchondromatosis, type VI. Halal and Azouz (1991) added 3 tentative categories to the 6 in the classification of Spranger et al. (1978). Pansuriya et al. (2010) suggested a new classification of enchondromatosis (multiple enchondromas).

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).

With the current widespread use of multigene panels and comprehensive genomic testing, it has become apparent that the phenotypic spectrum of EPG5-related disorder represents a continuum. At the most severe end of the spectrum is classic Vici syndrome (defined as a neurodevelopmental disorder with multisystem involvement characterized by the combination of agenesis of the corpus callosum, cataracts, hypopigmentation, cardiomyopathy, combined immunodeficiency, microcephaly, and failure to thrive); at the milder end of the spectrum are attenuated neurodevelopmental phenotypes with variable multisystem involvement. Median survival in classic Vici syndrome appears to be 24 months, with only 10% of children surviving longer than age five years; the most common causes of death are respiratory infections as a result of primary immunodeficiency and/or cardiac insufficiency resulting from progressive cardiac failure. No data are available on life span in individuals at the milder end of the spectrum.

Any severe combined immunodeficiency in which the cause of the disease is a mutation in the CD247 gene.

MHC class II deficiency-3 (MHC2D3) is a rare autosomal recessive immunodeficiency characterized by the onset of recurrent and persistent infections from birth. Infectious agents include bacteria, viruses, fungi, and protozoa, usually affecting the respiratory and gastrointestinal tract. Laboratory studies show decreased CD4+ T cells, hypogammaglobulinemia, an inverted CD4:CD8 ratio, and absence of MHC type II antigens (HLA-DR, -DQ, and -DP) on the surface of antigen-presenting cells. Most patients die in infancy or early childhood unless they undergo bone marrow transplantation, which can be curative, although complications are common. Rare patients may survive longer, even without bone marrow transplant. MHC class II deficiency may not be detected by newborn T-cell receptor excision circle (TREC) screening (summary by El Hawary et al., 2019; Mousavi Khorshidi et al., 2023). For a discussion of genetic heterogeneity of MHC class II deficiency, see MHC2D1 (209920).

T-cell immunodeficiency, congenital alopecia, and nail dystrophy (TIDAND) is an autosomal recessive primary immunodeficiency characterized by congenital thymic aplasia and severe T-cell immunodeficiency apparent at birth or soon thereafter. Affected individuals tend to have recurrent infections, oral candidiasis, and failure to thrive. Immunologic investigations show decreased numbers of T cells with poor proliferative response to phytohemagglutinin (PHA) and variable hypogammaglobulinemia. The phenotype is consistent with a T-/B+/NK+ form of severe combined immunodeficiency (SCID; see, e.g., 102700). Patients with FOXN1 mutations do not respond well to hematopoietic stem cell transplantation, as it is not curative; thymic transplantation offers a potential cure (Chou et al., 2014).

A rare, genetic, non-severe combined immunodeficiency disease characterized by immunodeficiency (manifested by recurrent and/or severe bacterial and viral infections), destructive noninfectious granulomas involving skin, mucosa and internal organs, and various autoimmune manifestations (including cytopenias, vitiligo, psoriasis, myasthenia gravis, enteropathy). Immunophenotypically, T-cell and B-cell lymphopenia, hypogammaglobulinemia, abnormal specific antibody production and impaired T-cell function are observed.

Immunodeficiency-68 (IMD68) is an autosomal recessive primary immunodeficiency characterized by severe systemic and invasive bacterial infections beginning in infancy or early childhood. The most common organisms implicated are Streptococcus pneumoniae, Staphylococcus aureus, and Pseudomonas, although other organisms may be observed. IMD68 is life-threatening in infancy and early childhood. The first invasive infection typically occurs before 2 years of age, with meningitis and upper respiratory infections being common manifestations. The mortality rate in early childhood is high, with most deaths occurring before 8 years of age. Affected individuals have an impaired inflammatory response to infection, including lack of fever and neutropenia, although erythrocyte sedimentation rate (ESR) and C-reactive protein may be elevated. General immunologic workup tends to be normal, with normal levels of B cells, T cells, and NK cells. However, more detailed studies indicate impaired cytokine response to lipopolysaccharide (LPS) and IL1B (147720) stimulation; response to TNFA (191160) is usually normal. Patients have good antibody responses to most vaccinations. Viral, fungal, and parasitic infections are generally not observed. Early detection is critical in early childhood because prophylactic treatment with IVIg or certain antibiotics is effective; the disorder tends to improve naturally around adolescence. At the molecular level, IMD68 results from impaired function of selective Toll receptor (see TLR4, 603030)/IL1R (see IL1R1; 147810) signaling pathways that ultimately activate NFKB (164011) to produce cytokines (summary by Picard et al., 2010). See also IMD67 (607676), caused by mutation in the IRAK4 gene (602170), which shows a similar phenotype to IMD68. As the MYD88 and IRAK4 genes interact in the same intracellular signaling pathway, the clinical and cellular features are almost indistinguishable (summary by Picard et al., 2010).

Activated PI3K delta syndrome (APDS) is characterized by a spectrum of clinical manifestations involving the immune system leading to increased susceptibility to infections (e.g., otitis media, sinusitis, bronchitis, and pneumonia), autoimmune/autoinflammatory manifestations including autoimmune cytopenias, gastrointestinal manifestations resembling Crohn-like colitis, intussusception, and lymphoproliferation (e.g., lymphadenopathy, hepatosplenomegaly, and nodular lymphoid hyperplasia), and an increased risk of developing B-cell lymphomas and other malignancies. Short stature, growth delays, and neurodevelopmental delays are also reported. APDS type 1 (APDS1) is caused by a heterozygous pathogenic gain-of-function variant in PIK3CD, and APDS type 2 (APDS2) is caused by a heterozygous loss-of-function pathogenic variant in PIK3R1. The key clinical differences between APDS1 and APDS2 include short stature, frequency of gastrointestinal infections, and characteristic dental findings, which are more prominent in APDS2.

Idiopathic CD4 lymphopenia (ICL) is a rare and heterogeneous syndrome defined by a reproducible reduction in the CD4 T-lymphocyte count (less than 300 cells per microliter or less than 20% of total T cells) in the absence of HIV infection or other known causes of immunodeficiency. ICL predisposes to infections and malignancy (summary by Gorska and Alam, 2012).

Immunodeficiency-17 (IMD17) is an autosomal recessive primary immunodeficiency characterized by highly variable clinical severity. Some patients have onset of severe recurrent infections in early infancy that may be lethal, whereas others may be only mildly affected or essentially asymptomatic into young adulthood. More severely affected patients may have evidence of autoimmune disease or enteropathy. The immunologic pattern is similar among patients, showing partial T-cell lymphopenia, particularly of cytotoxic CD8 (see 186910)-positive cells, decreased amounts of the CD3 complex, and impaired proliferative responses to T-cell receptor (TCR)-dependent stimuli. B cells, natural killer (NK) cells, and immunoglobulins are usually normal. Although thymic output of functional naive T cells early in life is decreased, polyclonal expansion of functional memory T cells is substantial. The phenotype in some patients is reminiscent of severe combined immunodeficiency (SCID) (summary by Timon et al. (1993) and Recio et al. (2007)).

Severe combined immunodeficiency-19 (IMD19) is an autosomal recessive disorder characterized by onset in early infancy of recurrent bacterial, viral, and fungal infections. Patients usually have chronic diarrhea, recurrent respiratory infections, and failure to thrive. Immunologic workup shows a T cell-negative, B cell-positive, natural killer (NK) cell-positive phenotype. The disorder is lethal in early childhood without bone marrow transplantation (summary by Yu et al., 2011).

Severe combined immunodeficiency (SCID) due to DNA-PKcs deficiency is an extremely rare type of SCID (see this term) characterized by the classical signs of SCID (severe and recurrent infections, diarrhea, failure to thrive), absence of T and B lymphocytes, and cell sensitivity to ionizing radiation.

Immunodeficiency-40 is an autosomal recessive primary form of combined immunodeficiency mainly affecting T-cell number and function, with other more variable defects in B-cell and NK-cell function. Patients have onset of severe invasive bacterial and viral infections in early childhood and may die without bone marrow transplantation (summary by Dobbs et al., 2015).

Any primary immunodeficiency disease in which the cause of the disease is a mutation in the BCL11B gene.

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, 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.

Vertebral anomalies and variable endocrine and T-cell dysfunction is a syndrome characterized by an overlapping spectrum of features. Skeletal malformations primarily involve the vertebrae, and endocrine abnormalities involving parathyroid hormone (PTH; 168450), growth hormone (GH1; 139250), and the thyroid gland have been reported. T-cell abnormalities have been observed, with some patients showing thymus gland aplasia or hypoplasia. Patients have mild craniofacial dysmorphism, and some show developmental delay or behavioral problems. Cardiac defects may be present (Liu et al., 2018).

Immunodeficiency-130 with HPV-related verrucosis (IMD130) an autosomal recessive form of combined immunodeficiency (CID) characterized mainly by the onset of warts and verrucous or plaque-like skin lesions associated with HPV infection, usually in the first 3 decades of life. There is an increased risk of skin malignancy. Some patients may have other symptoms of immune dysfunction, including mycobacterial, herpes simplex virus (HSV), or fungal infections. Immunologic workup shows T-cell lymphopenia, particularly affecting CD4+ T cells (Horev et al., 2015, Arango-Franco et al., 2024).

Infantile T-cell lymphopenia with or without nail dystrophy (TLIND) is an autosomal dominant disorder characterized by decreased numbers of T cells, particularly cytotoxic CD8+ T cells, usually apparent from infancy. Patients are often identified through newborn screening with the finding of low levels of T-cell receptor excision circles (TRECs). Affected individuals tend to be more susceptible to recurrent infections, mainly respiratory viral infections. However, the severity is highly variable, and patients usually improve with age later in childhood and as adults, even if CD8+ T cells remain decreased compared to normal. Additional features may include a small thymic shadow, indicative of impaired thymic development, skin abnormalities, such as atopic dermatitis, and nail dystrophy. As rare patients may develop more serious infections, affected individuals should be monitored. Bone marrow transplantation is not curative (summary by Bosticardo et al., 2019).

Immunodeficiency-73B with defective neutrophil chemotaxis (IMD73B) is an autosomal dominant immunologic disorder characterized by onset of recurrent infections in infancy or early childhood. Affected individuals develop respiratory infections, cellulitis, and severe invasive infections or sepsis; organisms include bacteria such as Staphylococcus, as well as viruses, fungi, and mycobacterial species. Laboratory studies show variable abnormalities, including B- and T-cell lymphopenia, decreased immunoglobulin subsets, decreased TRECs and dysfunctional T cells, decreased NK cells, neutropenia, and impaired neutrophil chemotaxis. Hematopoietic stem cell transplantation is curative (summary by Hsu et al., 2019; review by Lougaris et al., 2020). In a review of autosomal forms of chronic granulomatous disease (see 306400 for genetic heterogeneity of CGD), Roos et al. (2021) noted that patients with RAC2 mutations may manifest CGD-like symptoms due to defects in neutrophil NADPH oxidase activity.

Immunodeficiency-76 (IMD76) is an autosomal recessive primary immunologic disorder characterized by onset of recurrent bacterial, viral, and fungal infections in early childhood. Laboratory studies show T-cell lymphopenia and may show variable B-cell or immunoglobulin abnormalities. More variable features found in some patients include lymphoma and neurologic features. Although bone marrow transplantation may be curative, many patients die in childhood (summary by Lyszkiewicz et al., 2020).

Immunodeficiency-80 with or without congenital cardiomyopathy (IMD80) is an autosomal recessive immunologic disorder with variable manifestations. One patient with infantile-onset of chronic cytomegalovirus (CMV) infection associated with severely decreased NK cells has been reported. Another family with 3 affected fetuses showing restrictive cardiomyopathy and hypoplasia of the spleen and thymus has also been reported (summary by Baxley et al., 2021).

Immunodeficiency-82 with systemic inflammation (IMD82) is a complex autosomal dominant immunologic disorder characterized by recurrent infections with various organisms, as well as noninfectious inflammation manifest as lymphocytic organ infiltration with gastritis, colitis, and lung, liver, CNS, or skin disease. One of the more common features is inflammation of the stomach and bowel. Most patients develop symptoms in infancy or early childhood; the severity is variable. There may be accompanying fever, elevated white blood cell count, decreased B cells, hypogammaglobulinemia, increased C-reactive protein (CRP; 123260), and a generalized hyperinflammatory state. Immunologic workup shows variable B- and T-cell abnormalities such as skewed subgroups. Patients have a propensity for the development of lymphoma, usually in adulthood. At the molecular level, the disorder results from a gain-of-function mutation that leads to constitutive and enhanced activation of the intracellular inflammatory signaling pathway. Treatment with SYK inhibitors rescued human cell abnormalities and resulted in clinical improvement in mice (Wang 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).

Severe combined immunodeficiency-104 (IMD104) is an autosomal recessive disorder characterized by the onset of recurrent infections in early infancy. Manifestations may include oral thrush, fever, and failure to thrive. Some patients have lymphadenopathy and hepatosplenomegaly, whereas others have absence of lymph nodes and lack a thymic shadow. Laboratory studies show decreased or absent numbers of nonfunctional T cells, normal or increased levels of B cells, variable hypogammaglobulinemia, and normal NK cells. The disorder is caused by a defect in IL7 (146660) signaling due to a mutant IL7 receptor. Hematopoietic stem cell transplantation may be curative (Roifman et al., 2000 and Giliani et al., 2005). Giliani et al. (2005) provided a detailed review of IL7R deficiency, including discussion of the IL7R gene and its function in the immune system, clinical features of the disorder, and experiences with hematopoietic stem cell transplant as treatment. For a general phenotypic description and a discussion of genetic heterogeneity of autosomal recessive SCID, see 601457.

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.

Immunodeficiency-112 (IMD112) is an autosomal recessive primary immunologic disorder with variable manifestations beginning in early childhood. Some patients have recurrent bacterial, viral, and fungal infections, including disseminated bacillus Calmette-Guerin (BCG)-related infections, whereas at least 1 patient only presented with BCG-related infections. Immunologic workup shows variable abnormalities affecting lymphoid immunity, including hypogammaglobulinemia, lymphopenia or paradoxical lymphocytosis, and defects in B, T, and NK cell differentiation and function mainly due to disruption of the noncanonical NFKB (see 164011) signaling pathway (Willmann et al., 2014; Schlechter et al., 2017).

Immunodeficiency-115 with autoinflammation (IMD115) is an autosomal recessive disorder characterized by the onset of symptoms of immune dysregulation in early infancy. Affected individuals have immunodeficiency with recurrent bacterial, viral, and fungal infections, as well as autoinflammatory features, including arthritis and dermatitis. Some patients may have more systemic involvement, such as myopathy, gastrointestinal abnormalities, and anemia. Laboratory studies show variable B-cell and T-cell defects, sometimes with defective antibody responses and hypogammaglobulinemia (Boisson et al., 2015; Oda et al., 2019).

Immunodeficiency-117 (IMD117) is an autosomal recessive immunologic disorder characterized by increased susceptibility to disseminated mycobacterial infection apparent in early childhood. Affected individuals develop mycobacterial disease after BCG (bacille Calmette-Guerin) vaccination and show increased susceptibility to other mycobacterial infections, such as M. avium. Immunologic workup shows impaired development of myeloid and lymphoid cell subsets that secrete and respond to gamma-interferon (IFNG; 147570) (et al., 2023).

Immunodeficiency-121 with autoinflammation (IMD121) is a complex immunologic disorder characterized clinically by T-, B-, NK+/- severe combined immunodeficiency (SCID) associated with failure to thrive, erythrodermia, diarrhea, and alopecia. Symptom onset is in early infancy. Laboratory studies show lymphopenia with reduced or absent B cells, decreased T cells, skewed T-cell repertoire, and eosinophilia. Treatment with hematopoietic stem cell transplant (HSCT) is often complicated by severe inflammatory post-transplant complications (van der Made et al., 2024).

Immunodeficiency-122 (IMD122) is an autosomal recessive inborn error of immunity characterized by early-infantile onset of recurrent viral and bacterial infections of the respiratory tract and skin. Laboratory studies show severely decreased CD3+ T cells particularly affecting naive T cells, impaired early TCR recombination with a restricted TCR repertoire, normal or low-normal B cells, and decreased or increased NK cells. Affected individuals have poor overall growth, global developmental delay with poor motor skills, impaired intellectual development, and poor or absent speech acquisition. More variable findings may include diffuse skin rash, erythroderma, sensorineural hearing loss, lymphadenopathy, dysmorphic facial features, and tooth abnormalities. Death in early childhood may occur (Mehawej et al., 2023; Riestra et al., 2024).