A multifocal, multisystem form of Langerhans-cell histiocytosis. There is involvement of multiple organ systems including the bones, skin, liver, spleen, and lymph nodes. Patients are usually infants presenting with fever, hepatosplenomegaly, lymphadenopathy, bone and skin lesions, and pancytopenia.

Idiopathic hypereosinophilic syndrome (HES) is a myeloproliferative disorder in which persistent eosinophilia leads to tissue damage, caused by direct infiltration by eosinophils and cytokine release, which leads to progressive organ dysfunction that may be fatal (summary by Griffin et al., 2003).

Familial eosinophilia is a rare autosomal dominant disorder characterized by peripheral hypereosinophilia (greater than 500 eosinophils/micro liter of blood) with or without other oragn involvement (summary by Rioux et al., 1998).

Goodpasture syndrome, also known as anti-GBM disease, is a rare autoimmune disease consisting of alveolar hemorrhage and glomerulonephritis secondary to circulating antiglomerular basement membrane (anti-GBM) antibodies. Anti-GBM antibodies are directed against an antigen intrinsic to the alpha-3 chain of type IV collagen (COL4A3; 120070) that is expressed in the GBMs of the glomerular capillary loops and the basal membrane of the pulmonary alveoli. Goodpasture syndrome is suspected in patients with hemoptysis and hematuria and is confirmed by the presence of anti-GBM antibodies in renal biopsy specimens and serum. Patients with human leukocyte antigen HLA-DR15 and HLA-DR4 are susceptible to the development of Goodpasture syndrome. Reported cases of familial Goodpasture syndrome are extremely rare (summary by Angioi et al., 2017).

Immunodeficiency-41 (IMD41) 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).

Gaucher disease (GD) encompasses a continuum of clinical findings from a perinatal-lethal disorder to an asymptomatic type. The characterization of three major clinical types (1, 2, and 3) and two clinical forms (perinatal-lethal and cardiovascular) is useful in determining prognosis and management. Cardiopulmonary complications have been described with all the clinical phenotypes, although varying in frequency and severity. Type 1 GD is characterized by the presence of clinical or radiographic evidence of bone disease (osteopenia, focal lytic or sclerotic lesions, and osteonecrosis), hepatosplenomegaly, anemia, thrombocytopenia, lung disease, and the absence of primary central nervous system disease. Type 2 GD is characterized by primary central nervous system disease with onset before age two years, limited psychomotor development, and a rapidly progressive course with death by age two to four years. Type 3 GD is characterized by primary central nervous system disease with childhood onset, a more slowly progressive course, and survival into the third or fourth decade. The perinatal-lethal form is associated with ichthyosiform or collodion skin abnormalities or with nonimmune hydrops fetalis. The cardiovascular form is characterized by calcification of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supranuclear ophthalmoplegia.

NKX2-1-related disorders range from benign hereditary chorea (BHC) to choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress syndrome (also known as brain-lung-thyroid syndrome). Childhood-onset chorea, the hallmark feature of NKX2-1-related disorders, may or may not be associated with pulmonary disease or congenital hypothyroidism. Age of onset of chorea varies from early infancy (most commonly) to late childhood or adolescence and may progress into the second decade, after which it remains static or (rarely) remits. Pulmonary disease, the second most common manifestation, can include respiratory distress syndrome in neonates, interstitial lung disease in young children, and pulmonary fibrosis in older individuals. The risk for pulmonary carcinoma is increased in young adults with NKX2-1-related disorders. Thyroid dysfunction, occurring as a result of thyroid dysgenesis, can present as congenital or compensated hypothyroidism. In one review, 50% of affected individuals had the full brain-lung-thyroid syndrome, 30% had brain and thyroid involvement only, and 13% had chorea only.

Any sarcoidosis in which the cause of the disease is a mutation in the BTNL2 gene.

Any sarcoidosis in which the cause of the disease is a mutation in the HLA-DRB1 gene.

Granulomatosis with polyangiitis, formerly termed Wegener granulomatosis, is a systemic disease with a complex genetic background. It is characterized by necrotizing granulomatous inflammation of the upper and lower respiratory tract, glomerulonephritis, vasculitis, and the presence of antineutrophil cytoplasmatic autoantibodies (ANCAs) in patient sera. These ANCAs are antibodies to a defined target antigen, proteinase-3 (PR3, PRTN3; 177020), which is present within primary azurophil granules of neutrophils (PMNs) and lysozymes of monocytes. On cytokine priming of PMNs, PR3 translocates to the cell surface, where PR3-ANCAs can interact with their antigens and activate PMNs. PMNs from patients with active GPA express PR3 on their surface, produce respiratory burst, and release proteolytic enzymes after activation with PR3-ANCAs. The consequence is a self-sustaining inflammatory process (Jagiello et al., 2004).

Immunodeficiency-27A (IMD27A) results from autosomal recessive (AR) IFNGR1 deficiency. Patients with complete IFNGR1 deficiency have a severe clinical phenotype characterized by early and often fatal mycobacterial infections. The disorder can thus be categorized as a form of mendelian susceptibility to mycobacterial disease (MSMD). Bacillus Calmette-Guerin (BCG) and environmental mycobacteria are the most frequent pathogens, and infection typically begins before the age of 3 years. Plasma from patients with complete AR IFNGR1 deficiency usually contains large amounts of IFNG (147570), and their cells do not respond to IFNG in vitro. In contrast, cells from patients with partial AR IFNGR1 deficiency, which is caused by a specific mutation in IFNGR1, retain residual responses to high IFNG concentrations. Patients with partial AR IFNGR1 deficiency are susceptible to BCG and environmental mycobacteria, but they have a milder clinical disease and better prognosis than patients with complete AR IFNGR1 deficiency. The clinical features of children with complete AR IFNGR1 deficiency are usually more severe than those in individuals with AD IFNGR1 deficiency (IMD27B), and mycobacterial infection often occurs earlier (mean age of 1.3 years vs 13.4 years), with patients having shorter mean disease-free survival. Salmonellosis is present in about 5% of patients with AR or AD IFNGR1 deficiency, and other infections have been reported in single patients (review by Al-Muhsen and Casanova, 2008).

Immunodeficiency-40 (IMD40) 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).

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

VEXAS syndrome is an autoinflammatory syndrome caused by a somatic UBA1 (i.e., mosaic or postzygotic) pathogenic variant in hematopoietic stem cells. Because UBA1 is an X-linked gene, VEXAS syndrome mostly affects males; however, females account for about 4% of affected individuals. VEXAS syndrome, characterized by inflammatory and hematologic findings, typically affects males older than age 50 years. The most common inflammatory findings include recurrent fever, skin lesions, pulmonary infiltrates, recurrent chondritis, arthritis, pan ocular inflammation, and unprovoked venous thrombosis. Hematologic involvement includes macrocytic anemia, myelodysplastic syndrome (MDS), thrombocytopenia, monoclonal gammopathy of unknown significance, and vacuoles in myeloid and erythroid precursor cells.

Nephronophthisis-like nephropathy-2 (NPHPL2) is an autosomal recessive cystic kidney disease characterized by onset of progressive renal insufficiency in the first decades of life. Renal imaging and biopsy show corticomedullary cysts, tubular ectasia, tubular basement membrane disruption, and tubulointerstitial infiltrations. Patients eventually progress to end-stage renal failure, necessitating kidney transplantation or dialysis (summary by Hurd et al., 2013). For a general phenotypic description and a discussion of genetic heterogeneity of nephronophthisis, see NPHP1 (256100).

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