A disorder resulting from loss of function or tissue destruction of an organ or multiple organs, arising from humoral or cellular immune responses of the individual to his own tissue constituents. It may be systemic (e.g., systemic lupus erythematosus), or organ specific, (e.g., thyroiditis).

Type 1 diabetes mellitus (T1D), also designated insulin-dependent diabetes mellitus (IDDM), is a disorder of glucose homeostasis characterized by susceptibility to ketoacidosis in the absence of insulin therapy. It is a genetically heterogeneous autoimmune disease affecting about 0.3% of Caucasian populations (Todd, 1990). Genetic studies of T1D have focused on the identification of loci associated with increased susceptibility to this multifactorial phenotype. The classic phenotype of diabetes mellitus is polydipsia, polyphagia, and polyuria which result from hyperglycemia-induced osmotic diuresis and secondary thirst. These derangements result in long-term complications that affect the eyes, kidneys, nerves, and blood vessels.

Myasthenia gravis (MG) is an autoimmune disease in which antibodies bind to acetylcholine receptors or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. The antibodies induce weakness of skeletal muscles, which is the sole disease manifestation. The weakness can be generalized or localized, is more proximal than distal, and nearly always includes eye muscles, with diplopia and ptosis. The pattern of involvement is usually symmetric, apart from the eye involvement, which is often markedly asymmetric and involves several eye muscles. The weakness typically increases with exercise and repetitive muscle use (fatigue) and varies over the course of a day and from day to day, often with nearly normal muscle strength in the morning (summary by Gilhus, 2016).

The stiff-person syndrome (SPS) is most often an adult-onset sporadic acquired disorder characterized by progressive muscle stiffness with superimposed painful muscle spasms accompanied by electromyographic evidence of continuous motor activity at rest. SPS has been associated with autoimmune disorders, diabetes mellitus, thyrotoxicosis, and hypopituitarism with adrenal insufficiency (George et al., 1984). Approximately 60% of patients with SPS have antibodies to glutamic acid decarboxylase (GAD2, or GAD65; 138275), the rate-limiting enzyme in the synthesis of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), suggesting an immune-mediated pathogenesis (Folli et al., 1993). Approximately 10% of patients develop SPS as a paraneoplastic neurologic disorder associated with antibodies to amphiphysin (AMPH; 600418), an intracellular protein associated with neuronal synaptic vesicle endocytosis (Burns, 2005). See also congenital stiff-man syndrome, or hereditary hyperexplexia (149400), which is caused by mutations in subunits of the glycine receptor gene (GLRA1, 138491; GLRB, 138492). Meinck and Thompson (2002) provided a detailed review of stiff-person syndrome. They also discussed 2 possibly related conditions, progressive encephalomyelitis with rigidity (PERM), a more severe disorder with other neurologic features, and stiff-limb or stiff-leg syndrome, a focal disorder.

Polyagglutination refers to red blood cells that agglutinate upon exposure to almost all human sera, but not to autologous serum or the sera of newborns. The condition becomes apparent during blood typing and cross-matching in the laboratory (summary by Beck, 2000). Tn polyagglutination syndrome is an acquired clonal disorder characterized by the polyagglutination of red blood cells by naturally occurring anti-Tn antibodies following exposure of the Tn antigen on the surface of erythrocytes. Only a subset of red cells express the antigen, which can also be expressed on platelets and leukocytes. This condition may occur in healthy individuals who manifest asymptomatic anemia, leukopenia, or thrombocytopenia; however, there is also an association between the Tn antigen and leukemia or myelodysplastic disorders. The Tn antigen is an incompletely glycosylated membrane glycoprotein with an exposed N-acetylgalactosamine residue. The Tn antigen results from inactivation of C1GALT1C1, which encodes a chaperone required for the correct functioning of T-synthetase (C1GALT1; 610555), an enzyme essential for the correct biosynthesis of O-glycans. Absence of active T-synthetase results in exposure of GalNAc residues, with a proportion of these residues becoming sialylated and forming a sialyl-Tn antigen (summary by Vainchenker et al., 1985 and Crew et al., 2008).

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon form of T-cell non-Hodgkin lymphoma in which cytotoxic CD8 (see 186910)+ T cells infiltrate adipose tissue forming subcutaneous nodules. Both children and adults can be affected, with a median age at diagnosis of 36 years and a female gender bias. Most patients have accompanying systemic features such as fever or flank pain. A subset (about 20%) of patients develop hemophagocytic lymphohistiocytosis (HLH), usually associated with CD8+ T cells rimming adipocytes in the bone marrow. An infectious agent is not identified, and the disorder is believed to result from improperly activated inflammation. Immunosuppressive therapy may be helpful; hematopoietic bone marrow transplantation is usually curative (summary by Gayden et al., 2018). For a general discussion of genetic heterogeneity of HLH, see HLH1 (267700).

Sjogren syndrome is an autoimmune disease that mainly affects the exocrine glands. It is clinically characterized by keratoconjunctivitis sicca and xerostomia (Goransson et al., 2006). See 200400 for association of Sjogren syndrome with achalasia in sisters.

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

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).

Abnormally low level of eosinophils in the blood.

Alopecia areata is a genetically determined, immune-mediated disorder of the hair follicle with an estimated lifetime risk of approximately 2%, making it one of the most common human autoimmune diseases. It shows a spectrum of severity that ranges from patchy localized hair loss on the scalp to the complete absence of hair everywhere on the body (Gilhar and Kalish, 2006).

Pemphigus vulgaris (PV) is a rare, blistering autoimmune disease that affects the skin and mucous membranes. Patients have circulating antibody to an intercellular cement substance, and deposition in vivo of this antibody is a hallmark of the disease. The antibody appears to be pathogenetic, since newborn infants of mothers with pemphigus may have blisters, and newborn mice injected with the antibody from patients have clinical pemphigus. The disease is reported to have a particularly high incidence among Jews (summary by Ahmed et al., 1990).

RAS-associated leukoproliferative disorder is characterized by lymphadenopathy, splenomegaly, and variable autoimmune phenomena, including autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura, and neutropenia. Laboratory studies show an expansion of lymphocytes due to defective apoptosis, as well as significant autoantibodies. Some patients have recurrent infections, and there may be an increased risk of hematologic malignancy (summary by Oliveira, 2013 and Niemela et al., 2010). The disorder shows significant overlap with autoimmune lymphoproliferative syndrome (ALPS; 601859) and was originally designated ALPS IV.

A form of hereditary angioedema characterized by acute edema in subcutaneous tissues, viscera and/or the upper airway.

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.

Lack of production of either functional C1r or C1s protein, due to a genetic defect. Approximately 60% of patients with a C1r/C1s deficiency will develop a severe systemic lupus erythematosus at an early age. Patients also present with frequent sinopulmonary infections often with Streptococcus pneumoniae.

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.

C1q deficiency (C1QD) is a rare autosomal recessive disorder characterized by recurrent skin lesions, chronic infections, and an increased risk of autoimmune diseases, particularly systemic lupus erythematosus (SLE; see 152700) or SLE-like diseases. It has also been associated with chronic glomerulonephritis and renal failure. C1q deficiency presents in 2 different forms, absent C1q protein or presence of a dysfunctional molecule (summary by Topaloglu et al., 1996 and Vassallo et al., 2007). Genetic Heterogeneity of C1q Deficiency See also C1q deficiency-2 (C1QD2; 620321), caused by mutation in the C1QB gene (120570), and C1q deficiency-3 (C1QD3; 620322), caused by mutation in the C1QC gene (120575).

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).

Immunodeficiency-7 (IMD7) is an autosomal recessive immunologic disorder characterized by onset of recurrent bacterial and viral infections in infancy or early childhood. Affected individuals may also have features of immune dysregulation, including lymphadenopathy and presence of autoantibodies. Laboratory studies show increased serum IgE, low numbers of T cells, low TCR-alpha/beta cells, and increased TCR-gamma/delta cells. The disorder often results in death in childhood, although bone marrow transplant is effective (summary by Morgan et al., 2011 and Rawat et al., 2021).

Autoimmune lymphoproliferative syndrome type III is an autosomal recessive disorder of immune dysregulation. The phenotype is variable, but most patients have significant lymphadenopathy associated with variable autoimmune manifestations. Some patients may have recurrent infections. Lymphocyte accumulation results from a combination of impaired apoptosis and excessive proliferation (summary by Oliveira, 2013). For a general description and a discussion of genetic heterogeneity of ALPS, see 601859.

In addition to classic type 1 (see 222100) and type 2 (see 125853) diabetes mellitus, atypical presentations are seen, particularly in populations of African ancestry. Ketosis-prone diabetes, the most common atypical form, is characterized by an acute initial presentation with severe hyperglycemia and ketosis, as seen in classic type 1 diabetes, but after initiation of insulin therapy, prolonged remission is often possible with cessation of insulin therapy and maintenance of appropriate metabolic control. Metabolic studies show a markedly blunted insulin secretory response to glucose, partially reversible with the improvement of blood glucose control. Variable levels of insulin resistance are observed, especially in obese patients. Pancreatic beta-cell autoimmunity is a rare finding, and association with type 1 susceptibility HLA alleles is variable (Sobngwi et al., 2002).

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).

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.

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).

Any autoimmune disease, multisystem, infantile-onset in which the cause of the disease is a mutation in the ZAP70 gene.

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).

Periodontal Ehlers-Danlos syndrome (pEDS) is characterized by distinct oral manifestations. Periodontal tissue breakdown beginning in the teens results in premature loss of teeth. Lack of attached gingiva and thin and fragile gums lead to gingival recession. Connective tissue abnormalities of pEDS typically include easy bruising, pretibial plaques, distal joint hypermobility, hoarse voice, and less commonly manifestations such as organ or vessel rupture. Since the first descriptions of pEDS in the 1970s, 148 individuals have been reported in the literature; however, future in-depth descriptions of non-oral manifestations in newly diagnosed individuals with a molecularly confirmed diagnosis of pEDS will be important to further define the clinical features.

Hyper-IgE syndrome-2 with recurrent infections (HIES2) is an autosomal recessive immunologic disorder characterized by recurrent staphylococcal infections of the skin and respiratory tract, eczema, elevated serum immunoglobulin E, and hypereosinophilia. It is distinguished from autosomal dominant HIES1 (147060) by the lack of connective tissue and skeletal involvement (Renner et al., 2004). For a discussion of genetic heterogeneity of hyper-IgE syndrome, see 147060. See also TYK2 deficiency (611521), a clinically distinct disease entity that includes characteristic features of both autosomal recessive HIES2 and mendelian susceptibility to mycobacterial disease (MSMD; 209950) (Minegishi et al., 2006).

Immunodeficiency-63 with lymphoproliferation and autoimmunity (IMD63) is an autosomal recessive disorder characterized by immune dysregulation. Affected individuals present in infancy with features of both abnormal activation of certain immune signaling pathways, resulting in lymphoid proliferation, dermatitis, enteropathy, and hypergammaglobulinemia, as well as features of immunodeficiency, such as recurrent infections and increased susceptibility to viral infections, especially CMV. Laboratory studies show increased NK cells that show impaired differentiation, as well as abnormal T cell populations or responses. Some patients may die in childhood; hematopoietic bone marrow transplantation is curative (summary by Zhang et al., 2019).

Loeys-Dietz syndrome (LDS) is characterized by vascular findings (cerebral, thoracic, and abdominal arterial aneurysms and/or dissections), skeletal manifestations (pectus excavatum or pectus carinatum, scoliosis, joint laxity, arachnodactyly, talipes equinovarus, cervical spine malformation and/or instability), craniofacial features (widely spaced eyes, strabismus, bifid uvula / cleft palate, and craniosynostosis that can involve any sutures), and cutaneous findings (velvety and translucent skin, easy bruising, and dystrophic scars). Individuals with LDS are predisposed to widespread and aggressive arterial aneurysms and pregnancy-related complications including uterine rupture and death. Individuals with LDS can show a strong predisposition for allergic/inflammatory disease including asthma, eczema, and reactions to food or environmental allergens. There is also an increased incidence of gastrointestinal inflammation including eosinophilic esophagitis and gastritis or inflammatory bowel disease. Wide variation in the distribution and severity of clinical features can be seen in individuals with LDS, even among affected individuals within a family who have the same pathogenic variant.

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.