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Somatic mutations (also known as acquired mutations) are emerging as common, age-related processes that occur in all cells throughout the body. Somatic mutations are canonically linked to malignant processes but over the past decade have been increasingly causally connected to benign diseases including rheumatic conditions. Here we outline the contribution of somatic mutations to complex and monogenic immunological diseases with a detailed review of unique aspects associated with such causes. Somatic mutations can cause early- or late-onset rheumatic monogenic diseases but also contribute to the pathogenesis of complex inflammatory and immune-mediated diseases, affect disease progression and define new clinical subtypes. Although even variants with a low variant allele fraction can be pathogenic, clonal dynamics could lead to changes over time in the proportion of mutant cells, with possible phenotypic consequences for the individual. Thus, somatic mutagenesis and clonal expansion have relevant implications in genetic testing and counselling. On the basis of both increased recognition of somatic diseases in clinical practice and improved technical and bioinformatic processes, we hypothesize that there will be an ever-expanding list of somatic mutations in various genes leading to inflammatory conditions, particularly in late-onset disease.

Immunological health has been challenging to characterize but could be defined as the absence of immune pathology. While shared features of some immune diseases and the concept of immunologic resilience based on age-independent adaptation to antigenic stimulation have been developed, general metrics of immune health and its utility for assessing clinically healthy individuals remain ill defined. Here we integrated transcriptomics, serum protein, peripheral immune cell frequency and clinical data from 228 patients with 22 monogenic conditions impacting key immunological pathways together with 42 age- and sex-matched healthy controls. Despite the high penetrance of monogenic lesions, differences between individuals in diverse immune parameters tended to dominate over those attributable to disease conditions or medication use. Unsupervised or supervised machine learning independently identified a score that distinguished healthy participants from patients with monogenic diseases, thus suggesting a quantitative immune health metric (IHM). In ten independent datasets, the IHM discriminated healthy from polygenic autoimmune and inflammatory disease states, marked aging in clinically healthy individuals, tracked disease activities and treatment responses in both immunological and nonimmunological diseases, and predicted age-dependent antibody responses to immunizations with different vaccines. This discriminatory power goes beyond that of the classical inflammatory biomarkers C-reactive protein and interleukin-6. Thus, deviations from health in diverse conditions, including aging, have shared systemic immune consequences, and we provide a web platform for calculating the IHM for other datasets, which could empower precision medicine.

The linear ubiquitin assembly complex (LUBAC) consists of HOIP, HOIL-1 and SHARPIN and is essential for proper immune responses. Individuals with HOIP and HOIL-1 deficiencies present with severe immunodeficiency, autoinflammation and glycogen storage disease. In mice, the loss of Sharpinleads to severe dermatitis due to excessive keratinocyte cell death. Here, we report two individuals with SHARPIN deficiency who manifest autoinflammatory symptoms but unexpectedly no dermatological problems. Fibroblasts and B cells from these individuals showed attenuated canonical NF-κB responses and a propensity for cell death mediated by TNF superfamily members. Both SHARPIN-deficient and HOIP-deficient individuals showed a substantial reduction of secondary lymphoid germinal center B cell development. Treatment of one SHARPIN-deficient individual with anti-TNF therapies led to complete clinical and transcriptomic resolution of autoinflammation. These findings underscore the critical function of the LUBAC as a gatekeeper for cell death-mediated immune dysregulation in humans.

Monogenic autoinflammatory diseases are a group of rheumatologic disorders caused by dysregulation in the innate immune system. The molecular mechanisms of these disorders are linked to defects in inflammasome-mediated, NF-κB-mediated or interferon-mediated inflammatory signalling pathways, cytokine receptors, the actin cytoskeleton, proteasome complexes and various enzymes. As with other human disorders, disease-causing variants in a single gene can present with variable expressivity and incomplete penetrance. In some cases, pathogenic variants in the same gene can be inherited either in a recessive or dominant manner and can cause distinct and seemingly unrelated phenotypes, although they have a unifying biochemical mechanism. With an enhanced understanding of protein structure and functionality of protein domains, genotype–phenotype correlations are beginning to be unravelled. Many of the mutated proteins are primarily expressed in haematopoietic cells, and their malfunction leads to systemic inflammation. Disease presentation is also defined by a specific effect of the mutant protein in a particular cell type and, therefore, the resulting phenotype might be more deleterious in one tissue than in another. Many patients present with the expanded immunological disease continuum that includes autoinflammation, immunodeficiency, autoimmunity and atopy, which necessitate genetic testing.

Background: Familial Mediterranean fever is a recessively inherited disorder characterized by episodes of fever with abdominal pain, pleurisy, or arthritis. The familial Mediterranean fever gene, designated MEFV, was recently cloned, and at least three missense mutations (M6801, M694V, and V726A) that account for a large percentage of patients with this disease were identified. Objective: To establish a diagnostic test for familial Mediterranean fever. Design: Cross-sectional study of a convenience sample of patients attending familial Mediterranean fever clinics. Setting: Tertiary referral hospitals. Patients: 107 patients with familial Mediterranean fever, their family members, and controls. Measurements: Mutations in the 107 samples were assessed by amplifying genomic DNA with use of primers that selectively amplify the normal or altered DNA sequence of the 3 MEFV mutations (amplification refractory mutation system [ARMS]). Mutations were independently assessed by automated sequencing of genomic DNA amplified by polymerase chain reaction to evaluate the sensitivity and specificity of the ARMS assay. Results: The ARMS assay correctly identified M6801, M694V, and V726A mutations in 82 persons with mutations documented by DNA sequencing (21 homozygotes, 2 compound heterozygotes, and 59 simple heterozygotes). Of 7 persons known from family studies to be noncarriers and 18 unrelated persons who were negative for these mutations by sequencing, none had MEFV mutations according to ARMS. Conclusion: The ARMS assay is a rapid, cost-effective, and accurate method for detecting three common mutations in familial Mediterranean fever., A diagnostic test called the amplification refractory mutation system (ARMS) appears to be effective in identifying people with familial Mediterranean fever. This disease is characterized by fever, abdominal pain, joint inflammation and a lung condition called pleurisy. The gene associated with this disease was identified in 1997. Researchers used ARMS to screen 107 people with the disease, their family members and a group of healthy volunteers. The test correctly identified 82 people with mutations in the gene but did not detect the mutation in the healthy volunteers.

ObjectiveMajeed syndrome (MJS) is an autosomal recessive, systemic autoinflammatory disease (SAID) caused by biallelic loss-of-function variants in the LPIN2gene. It is characterized by early-onset chronic recurrent multifocal osteomyelitis (CRMO), dyserythropoietic anemia, and neutrophilic dermatosis. We analyzed a cohort of uncharacterized Indian patients for pathogenic variants in LPIN2and other genes associated with SAIDs.MethodsWe performed whole-exome sequencing (WES) for 1 patient and next-generation sequencing (NGS) targeted gene panel for SAIDs in 3 patients. One patient was a referral from neurology after clinical exome sequencing identified a novel variant in LPIN2. We reviewed the literature for all published studies of mutation-positive MJS patients and have summarized their clinical features and disease-causing variants.ResultsWe describe the largest series of patients with MJS outside of the Middle East. All 5 patients are homozygous for novel, possibly pathogenic variants in the LPIN2gene. Two of these variants are missense substitutions, and 3 are predicted to alter transcript splicing and create a truncated protein. In addition to the classical features of CRMO and anemia, patients exhibited previously unreported features, including abdominal pain, recurrent diarrhea/ear discharge, and erythema nodosum.ConclusionPatients with MJS may present initially to different specialists, and thus it is important to create awareness in the medical community. In India, consanguinity is a common sociocultural factor in many ethnic communities and an abbreviated NGS gene panel for autoinflammatory diseases should include MJS. The unavailability of interleukin 1 inhibitors in some countries poses a treatment challenge.

NF‐κB is a master transcription factor that activates the expression of target genes in response to various stimulatory signals. Activated NF‐κB mediates a plethora of diverse functions including innate and adaptive immune responses, inflammation, cell proliferation, and NF‐κB is regulated through interactions with IκB inhibitory proteins, which are in turn regulated by the inhibitor of κB kinase (IKK) complex. Together, these 3 components form the core of the NF‐κB signalosomes that have cell‐specific functions which are dependent on the interactions with other signaling molecules and pathways. The activity of NF‐κB pathway is also regulated by a variety of post‐translational modifications including phosphorylation and ubiquitination by Lys63, Met1, and Lys48 ubiquitin chains. The physiologic role of NF‐κB is best studied in the immune system due to discovery of many human diseases caused by pathogenic variants in various proteins that constitute the NF‐κB pathway. These disease‐causing variants can act either as gain‐of‐function (GoF) or loss‐of‐function (LoF) and depending on the function of mutated protein, can cause either immunodeficiency or systemic inflammation. Typically, pathogenic missense variants act as GoF and they lead to increased activity in the pathway. LoF variants can be inherited as recessive or dominant alleles and can cause either a decrease or an increase in pathway activity. Dominantly inherited LoF variants often result in haploinsufficiency of inhibitory proteins. Here, we review human Mendelian immunologic diseases, which results from mutations in different molecules in the canonical NF‐κB pathway and surprisingly present with a continuum of clinical features including immunodeficiency, atopy, autoimmunity, and autoinflammation. Pathogenic variants in proteins of the canonical NF‐κB signalosome were linked to a number of immunological diseases presenting with immunodeficiency, atopy, autoimmunity, autoinflammation, and cancer.

Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by homozygous or compound heterozygous gain-of-function mutations in MEFV, which encodes pyrin, an inflammasome protein. Heterozygous carrier frequencies for multiple MEFVmutations are high in several Mediterranean populations, suggesting that they confer selective advantage. Among 2,313 Turkish people, we found extended haplotype homozygosity flanking FMF-associated mutations, indicating evolutionarily recent positive selection of FMF-associated mutations. Two pathogenic pyrin variants independently arose >1,800 years ago. Mutant pyrin interacts less avidly with Yersinia pestisvirulence factor YopM than with wild-type human pyrin, thereby attenuating YopM-induced interleukin (IL)-1β suppression. Relative to healthy controls, leukocytes from patients with FMF harboring homozygous or compound heterozygous mutations and from asymptomatic heterozygous carriers released heightened IL-1β specifically in response to Y.pestis. Y.pestis-infected MefvM680I/M680IFMF knock-in mice exhibited IL-1-dependent increased survival relative to wild-type knock-in mice. Thus, FMF mutations that were positively selected in Mediterranean populations confer heightened resistance to Y.pestis.

Activation of RIPK1 controls TNF-mediated apoptosis, necroptosis and inflammatory pathways1. Cleavage of human and mouse RIPK1 after residues D324 and D325, respectively, by caspase-8 separates the RIPK1 kinase domain from the intermediate and death domains. The D325A mutation in mouse RIPK1 leads to embryonic lethality during mouse development2,3. However, the functional importance of blocking caspase-8-mediated cleavage of RIPK1 on RIPK1 activation in humans is unknown. Here we identify two families with variants in RIPK1 (D324V and D324H) that lead to distinct symptoms of recurrent fevers and lymphadenopathy in an autosomal-dominant manner. Impaired cleavage of RIPK1 D324 variants by caspase-8 sensitized patients’ peripheral blood mononuclear cells to RIPK1 activation, apoptosis and necroptosis induced by TNF. The patients showed strong RIPK1-dependent activation of inflammatory signalling pathways and overproduction of inflammatory cytokines and chemokines compared with unaffected controls. Furthermore, we show that expression of the RIPK1 mutants D325V or D325H in mouse embryonic fibroblasts confers not only increased sensitivity to RIPK1 activation-mediated apoptosis and necroptosis, but also induction of pro-inflammatory cytokines such as IL-6 and TNF. By contrast, patient-derived fibroblasts showed reduced expression of RIPK1 and downregulated production of reactive oxygen species, resulting in resistance to necroptosis and ferroptosis. Together, these data suggest that human non-cleavable RIPK1 variants promote activation of RIPK1, and lead to an autoinflammatory disease characterized by hypersensitivity to apoptosis and necroptosis and increased inflammatory response in peripheral blood mononuclear cells, as well as a compensatory mechanism to protect against several pro-death stimuli in fibroblasts.

RIPK1 is a key regulator of innate immune signalling pathways. To ensure an optimal inflammatory response, RIPK1 is regulated post-translationally by well-characterized ubiquitylation and phosphorylation events, as well as by caspase-8-mediated cleavage1–7. The physiological relevance of this cleavage event remains unclear, although it is thought to inhibit activation of RIPK3 and necroptosis8. Here we show that the heterozygous missense mutations D324N, D324H and D324Y prevent caspase cleavage of RIPK1 in humans and result in an early-onset periodic fever syndrome and severe intermittent lymphadenopathy—a condition we term ‘cleavage-resistant RIPK1-induced autoinflammatory syndrome’. To define the mechanism for this disease, we generated a cleavage-resistant Ripk1D325Amutant mouse strain. Whereas Ripk1−/−mice died postnatally from systemic inflammation, Ripk1D325A/D325Amice died during embryogenesis. Embryonic lethality was completely prevented by the combined loss of Casp8and Ripk3, but not by loss of Ripk3or Mlklalone. Loss of RIPK1 kinase activity also prevented Ripk1D325A/D325Aembryonic lethality, although the mice died before weaning from multi-organ inflammation in a RIPK3-dependent manner. Consistently, Ripk1D325A/D325Aand Ripk1D325A/+cells were hypersensitive to RIPK3-dependent TNF-induced apoptosis and necroptosis. Heterozygous Ripk1D325A/+mice were viable and grossly normal, but were hyper-responsive to inflammatory stimuli in vivo. Our results demonstrate the importance of caspase-mediated RIPK1 cleavage during embryonic development and show that caspase cleavage of RIPK1 not only inhibits necroptosis but also maintains inflammatory homeostasis throughout life.

Reduction of adenosine deaminase 2 (ADA2) activity due to autosomal-recessive loss-of-function mutations in the ADA2 gene (previously known as CECR1) results in a systemic vasculitis known as deficiency of ADA2 (DADA2). Neutrophils and a subset of neutrophils known as low-density granulocytes (LDGs) have been implicated in the pathogenesis of vasculitis, at least in part, through the formation of neutrophil extracellular traps (NETs). The study objective was to determine whether neutrophils and NETs play a pathogenic role in DADA2. In vivo evidence demonstrated NETs and macrophages in affected gastrointestinal tissue from patients with DADA2. An abundance of circulating LDGs prone to spontaneous NET formation was observed during active disease in DADA2 and were significantly reduced after remission induction by anti–tumor necrosis factor (TNF) therapy. Increased circulating LDGs were identified in unaffected family members with monoallelic ADA2 mutations. Adenosine triggered NET formation, particularly in neutrophils from female patients, by engaging A1 and A3 adenosine receptors (ARs) and through reactive oxygen species– and peptidylarginine deiminase–dependent pathways. Adenosine-induced NET formation was inhibited by recombinant ADA2, A1/A3 AR antagonists, or by an A2A agonist. M1 macrophages incubated with NETs derived from patients with DADA2 released significantly greater amounts of TNF-a. Treatment with an A2AAR agonist decreased nuclear translocation of NF-?B and subsequent production of inflammatory cytokines in DADA2 monocyte-derived macrophages. These results suggest that neutrophils may play a pathogenic role in DADA2. Modulation of adenosine-mediated NET formation may contribute a novel and directed therapeutic approach in the treatment of DADA2 and potentially other inflammatory diseases.

Kastner and colleagues review monogenic autoinflammatory diseases and their molecular mechanisms and explore the overlap among autoinflammation, autoimmunity and immunodeficiency.

Systemic autoinflammatory diseases are driven by abnormal activation of innate immunity. Herein we describe a new disease caused by high-penetrance heterozygous germline mutations in TNFAIP3, which encodes the NF-κB regulatory protein A20, in six unrelated families with early-onset systemic inflammation. The disorder resembles Behçet's disease, which is typically considered a polygenic disorder with onset in early adulthood. A20 is a potent inhibitor of the NF-κB signaling pathway. Mutant, truncated A20 proteins are likely to act through haploinsufficiency because they do not exert a dominant-negative effect in overexpression experiments. Patient-derived cells show increased degradation of IκBα and nuclear translocation of the NF-κB p65 subunit together with increased expression of NF-κB–mediated proinflammatory cytokines. A20 restricts NF-κB signals via its deubiquitinase activity. In cells expressing mutant A20 protein, there is defective removal of Lys63-linked ubiquitin from TRAF6, NEMO and RIP1 after stimulation with tumor necrosis factor (TNF). NF-κB–dependent proinflammatory cytokines are potential therapeutic targets for the patients with this disease.

Systemic autoinflammatory diseases are caused by abnormal activation of the cells that mediate innate immunity. In the past two decades, single-gene defects in different pathways, driving clinically distinct autoinflammatory syndromes, have been identified. Studies of these aberrant pathways have substantially advanced understanding of the cellular mechanisms that contribute to mounting effective and balanced innate immune responses. For example, mutations affecting the function of cytosolic immune sensors known as inflammasomes and the IL-1 signalling pathway can trigger excessive inflammation. A surge in discovery of new genes associated with autoinflammation has pointed to other mechanisms of disease linking innate immune responses to a number of basic cellular pathways, such as maintenance of protein homeostasis (proteostasis), protein misfolding and clearance, endoplasmic reticulum stress and mitochondrial stress, metabolic stress, autophagy and abnormalities in differentiation and development of myeloid cells. Although the spectrum of autoinflammatory diseases has been steadily expanding, a substantial number of patients remain undiagnosed. Next-generation sequencing technologies will be instrumental in finding disease-causing mutations in as yet uncharacterized diseases. As more patients are reported to have clinical features of autoinflammation and immunodeficiency or autoimmunity, the complex interactions between the innate and adaptive immune systems are unveiled.

Immune responses require a delicate balance: a weak response can cause immunodeficiency, whereas an excessive response can lead to hyperinflammatory disease and hematological malignancy. Because spleen tyrosine kinase has roles in multiple signaling pathways, its gain-of-function alterations in humans cause hypogammaglobulinemia as well as autoinflammation and predisposition to B cell lymphoma.

BACKGROUND Deficiency of interleukin 1 receptor antagonist (DIRA) is a recently described autoinflammatory syndrome of skin and bone caused by recessive mutations in the gene encoding the interleukin 1 receptor antagonist. Few studies have been published about this debilitating condition. Early identification is critical for targeted lifesaving intervention. OBSERVATIONS A male infant, born to nonconsanguineous Puerto Rican parents, was referred for management of a pustular eruption diagnosed as pustular psoriasis. At 2 months of age, the infant developed a pustular eruption. After extensive evaluation, he was confirmed to be homozygous for a 175-kb genomic deletion on chromosome 2 that includes the IL1RN gene, commonly found in Puerto Ricans. Therapy with anakinra was initiated, with rapid clearance of skin lesions and resolution of systemic inflammation. CONCLUSIONS Recent identification of DIRA as a disease entity, compounded by the limited number of reported cases, makes early identification difficult. It is critical to consider this entity in the differential diagnosis of infantile pustulosis. Targeted therapy with the recombinant human interleukin 1 receptor antagonist anakinra can be lifesaving if initiated early. A high carrier frequency of the 175-kb DIRA-associated genomic deletion in the Puerto Rican population strongly supports testing infants presenting with unexplained pustulosis in patients from this geographic region.

Adult-onset Still's disease (AOSD), an autoinflammatory syndrome of unknown etiology, typically manifests with spiking fevers, polyarthritis, and characteristic evanescent rash. We describe a young woman with AOSD complicated by calf fasciitis that serendipitously responded to clarithromycin administered for another indication. Remarkable improvement followed rechallenges with clarithromycin for subsequent AOSD flares. In addition to their antibacterial actions, macrolides demonstrate immunomodulatory effects, including suppression of proinflammatory cytokine production and neutrophil action. Previous clinical trials provide promising preliminary evidence of a therapeutic effect of macrolides in chronic inflammatory diseases. Although AOSD pathogenesis remains unclear, a role for dysregulation of innate immunity is supported by recent literature. Based on this possible innate immune mechanism, we suspect that macrolides may have induced a therapeutic response in this patient with AOSD. A clinical trial is warranted to establish or refute their therapeutic efficacy.

The term autoinflammation was initially coined to distinguish disorders characterized by recurrent episodes of inflammation in the absence of high-titer autoantibodies and antigen-specific T cells from the more common autoimmune diseases. Although this concept originally applied to monogenic hereditary recurrent fevers, it has expanded over time to include polygenic (complex) autoinflammatory diseases. Understanding of the pathogenesis of autoinflammatory diseases has grown rapidly in the past decade owing to advances in genome research and technology. Genome-wide linkage analysis, positional cloning, homozygosity mapping and candidate gene screening have led to the identification of mutations in 12 genes that are associated with monogenic diseases. Genome-wide association studies have begun to elucidate the molecular basis of complex autoinflammatory diseases. The discovery of disease-causing genetic variants has defined autoinflammation as disorder within the innate immune system, implicating IL-1 as a master cytokine, and has led to a breakthrough in therapy, with IL-1 inhibitors producing rapid and sustained amelioration of symptoms. Despite major advances, however, a substantial number of patients have no mutations in the known autoinflammatory genes. The challenge now is to find the undiscovered genes, considering that most cases are sporadic or occur within small families. New approaches and tools such as next-generation sequencing are discussed.

PAPA syndrome (Pyogenic Arthritis, Pyoderma gangrenosum, and Acne) is an autosomal dominant, hereditary auto-inflammatory disease arising from mutations in the PSTPIP1/CD2BP1 gene on chromosome 15q. These mutations produce a hyper-phosphorylated PSTPIP1 protein and alter its participation in activation of the “inflammasome” involved in interleukin-1 (IL-1) production. Overproduction of IL-1 is a clear molecular feature of PAPA syndrome. Ongoing research is implicating other biochemical pathways that may be relevant to the distinct pyogenic inflammation of the skin and joints characteristic of this disease. This review summarizes the recent and rapidly accumulating knowledge on these molecular aspects of PAPA syndrome and related disorders.

Somatic mutations in UBA1in hematopoietic stem cells and myeloid cells have recently been described and are associated with adult-onset severe autoinflammatory diseases including relapsing polychondritis, Sweet syndrome, polyarteritis nodosa, and giant cell arteritis. This newly defined syndrome is named VEXAS (vacuoles, E1, X-linked, autoinflammatory, somatic). We performed clinicopathologic, cytogenetic, flow cytometric and molecular bone marrow assessment of 15 patients diagnosed with VEXAS and peripheral cytopenias. All patients were male, with a median age of 64y (IQR 45-80) and all had somatic missense mutations affecting the p.Met41 residue in UBA1with variant allele frequencies (VAF) over 20% from peripheral blood or bone marrow samples and with lineage restriction to mature myeloid cells. Germline mutations at this residue are not reported in any public databases. Peripheral blood findings included macrocytic anemia in all patients (100%), thrombocytopenia in 9/15, and neutropenia in 1/15. All bone marrow aspirates (15/15; 100%) showed prominent vacuolization of both myeloid and erythroid precursors with few vacuoles noted in mature cells. Of the 9 patients tested for serum copper levels all were normal or borderline low. Marrow was hypercellular with granulocytic and megakaryocytic hyperplasia in 12/15 (80%). Definitive WHO criteria for MDS was met in 5/15 (40%) with 3 cases of MDS-MLD, and 2 of MDS-SLD. The remaining cases were suspicious for MDS with low or borderline levels of dyspoiesis that did not exceed greater than 10% of cells in respective lineages meeting criteria for clonal cytopenia of undetermined significance (CCUS). Of the MDS cases, dysplasia was seen in megakaryocytes (5/5), myeloid (2/5) and erythroid (1/5) precursors. Cytogenetic abnormalities were detected in 2/5 MDS patients involving t(3;12)(q21;q13) in one case, and del (5q)/del (13q) in another case. Next generation sequencing analyses were performed in 9/15 patients and showed mutations in DNMT3Ain 2/5 MDS cases (VAF 43% and 44%), CSF1Rin 1/5 MDS (VAF 3.1%), GNA11in 1/5 MDS (VAF3.3%) and EZH2mutation (VAF 22%) in one of the patients without overt MDS. Clonal plasma cell or B-cell populations were diagnosed in 6/15 patients with 3 plasma cell dyscrasias, and 2 cases of monoclonal B-cell lymphocytosis. The most common abnormalities detected by bone marrow flow cytometry analysis were severely reduced or absent B-cell precursors, inverted CD4:CD8 ratios and abnormal expression of CD56 on monocytes.

Young: Novartis: Research Funding.

Neonatal-onset multisystem inflammatory disease (NOMID)/chronic infantile neurologic, cutaneous, and articular syndrome is an autoinflammatory disease characterized by urticarial rash, arthropathy, and central nervous system inflammation.

The authors review the genes, and their respective proteins, responsible for eight autoinflammatory conditions. Familial Mediterranean fever is caused by mutations in pyrin, which is the prototype of a new family of proteins belonging to the death-domain superfamily. This new group of proteins, which regulate apoptosis, inflammation, and cytokine processing, share an approximately 90-amino-acid N-terminal sequence called the PYRIN domain. Mutations in another PYRIN domain protein, termed cryopyrin, are responsible for three clinically defined illnesses, Muckle-Wells syndrome, familial cold autoinflammatory syndrome, and NOMID/CINCA. A related protein encoded by the gene CARD15/NOD2is responsible for the Mendelian disorder, Blau syndrome, and also predisposes to Crohn disease. The gene responsible for PAPA syndrome has recently been identified as CD2BP1, and preliminary results from the authors' laboratory also implicate its protein product in these pathways. Lastly, the authors discuss the broadening genetic and clinical spectrum of TRAPS, an autoinflammatory syndrome resulting from mutations in the 55-kDa receptor for tumor necrosis factor.

To review the remarkable recent progress in our understanding of a range of inflammatory conditions in humans that until recently appeared unrelated. The term autoinflammatory disease has been proposed to describe a group of disorders characterized by attacks of seemingly unprovoked inflammation without significant levels of autoantibodies and autoreactive T cells.

Neonatal-onset multisystem inflammatory disease (NOMID; also known as chronic infantile neurologic, cutaneous, articular [CINCA] syndrome) is characterized by fever, chronic meningitis, uveitis, sensorineural hearing loss, urticarial skin rash, and a characteristic deforming arthropathy. We investigated whether patients with this disorder have mutations in CIAS1, the gene which causes Muckle-Wells syndrome and familial cold autoinflammatory syndrome, two dominantly inherited disorders with some similarities to NOMID/CINCA syndrome. Genomic DNA from 13 patients with classic manifestations of NOMID/CINCA syndrome and their available parents was screened for CIAS1 mutations by automated DNA sequencing. Cytokine messenger RNA (mRNA) levels were assessed by real-time polymerase chain reaction on peripheral blood leukocyte mRNA, and serum cytokine levels were assayed by enzyme-linked immunosorbent assay. Protein expression was assessed by Western blotting of lysates from plastic-adherent peripheral blood mononuclear cells. In 6 of the 13 patients, we found 6 heterozygous missense substitutions in CIAS1. Five of the 6 mutations are novel. None of these sequence changes was observed in a panel of >900 chromosomes from healthy controls. Two distinct nucleotide changes in a single codon in unrelated patients resulted in the same amino acid change. In 4 mutation-positive children whose parental DNA was available, no mutation was found in the parental DNA, supporting the conclusion that the mutations arose de novo. Consistent with the recently discovered role of CIAS1 in the regulation of interleukin-1 (IL-1), we found evidence of increased IL-1β, as well as tumor necrosis factor, IL-3, IL-5, and IL-6, but not transforming growth factor β, in a mutation-positive patient compared with normal controls. Our data increase the total number of known germline mutations in CIAS1 to 20, causing a spectrum of diseases ranging from familial cold autoinflammatory syndrome to Muckle-Wells syndrome to NOMID/CINCA syndrome. Mutations in CIAS1 were only found in ~50% of the cases identified clinically as NOMID/CINCA syndrome, which raises the possibility of genetic heterogeneity. IL-1 regulation by CIAS1 suggests that IL-1 receptor blockade may constitute a rational approach to the treatment of NOMID/CINCA syndrome.

Familial Mediterranean fever (FMF) is a recessive disorder characterized by episodes of fever and intense inflammation. FMF attacks are unique in their sensitivity to the microtubule inhibitor colchicine, contrasted with their refractoriness to the anti-inflammatory effects of glucocorticoids. The FMF gene,MEFV, was recently identified by positional cloning; it is expressed at high levels in granulocytes and monocytes. The present study investigated the subcellular localization of the normal gene product, pyrin. These experiments did not support previously proposed nuclear or Golgi localizations. Instead fluorescence microscopy demonstrated colocalization of full-length GFP- and epitope-tagged pyrin with microtubules; this was markedly accentuated in paclitaxel-treated cells. Moreover, immunoblot analysis of precipitates of stabilized microtubules with recombinant pyrin demonstrated a direct interaction in vitro. Pyrin expression did not affect the stability of microtubules. Deletion constructs showed that the unique N-terminal domain of pyrin is necessary and sufficient for colocalization, whereas disease-associated mutations in the C-terminal B30.2 (rfp) domain did not disrupt this interaction. By phalloidin staining, a colocalization of pyrin with actin was also observed in perinuclear filaments and in peripheral lamellar ruffles. The proposal is made that pyrin regulates inflammatory responses at the level of leukocyte cytoskeletal organization and that the unique therapeutic effect of colchicine in FMF may be dependent on this interaction.

Apolipoprotein E (apoE) is associated with senile plaques in Alzheimer's disease (AD), and present in amyloid deposits in a variety of systemic amyloidoses. Recently, studies have shown that apoE4 allelic frequency is increased in patients with sporadic and familial late-onset AD and that apoE4 may represent a susceptibility gene for late-onset AD. We addressed the issue of whether a similar association of apoE4 exists in a number of systemic amyloidoses. Tissue was obtained from control subjects, AD patients, familial Mediterranean fever (FMF) patients, amyloid A (AA) amyloid secondary to juvenile chronic arthritis (JCA), and amyloid of the light chain type (myeloma or AL). There was a strong correlation of the apoE4 allele with sporadic and late-onset AD, but no significant increase in apoE4 with other amyloidoses. These data suggest that whereas apoE4 may be a risk factor in AD, it is not in other amyloidoses. However, given the association of apoE with all these amyloidoses, the possibility cannot be excluded that this apolipoprotein could be involved in systemic amyloidoses on an isotype non-selective basis.

In this paper we describe the assembly and restriction map of a 1.05-Mb cosmid contig spanning the candidate region for familial Mediterranean fever (FMF), a recessively inherited disorder of inflammation localized to 16p13.3. Using a combination of cosmid walking and screening for P1, PAC, BAC, and YAC clones, we have generated a contig of genomic clones spanning ∼1050 kb that contains the FMF critical region. The map consists of 179 cosmid, 15 P1, 10 PAC, 3 BAC, and 17 YAC clones, anchored by 27 STS markers. Eight additional STSs have been developed from the ∼700 kb immediately centromeric to this genomic region. Five of the 35 STSs are microsatellites that have not been previously reported.NotI andEcoRI mapping of the overlapping cosmids, hybridization of restriction fragments from cosmids to one another, and STS analyses have been used to validate the assembly of the contig. Our contig totally subsumes the 250-kb interval recently reported, by founder haplotype analysis, to contain the FMF gene. Thus, our high-resolution clone map provides an ideal resource for transcriptional mapping toward the eventual identification of this disease gene.

Familial Mediterranean fever (FMF) is a recessive disorder of inflammation caused by mutations in a gene (designatedMEFV) on chromosome 16p13.3. We have recently constructed a 1-Mb cosmid contig that includes the FMF critical region. Here we show genotype data for 12 markers from our physical map, including 5 newly identified microsatellites, in FMF families. Intrafamilial recombinations placedMEFVin the ∼285 kb betweenD16S468/D16S3070andD16S3376.We observed significant linkage disequilibrium in the North African Jewish population, and historical recombinants in the founder haplotype placedMEFVbetweenD16S3082andD16S3373(∼200 kb). In smaller panels of Iraqi Jewish, Arab, and Armenian families, there were significant allelic associations only forD16S3370andD16S2617among the Armenians. A sizable minority of Iraqi Jewish and Armenian carrier chromosomes appeared to be derived from the North African Jewish ancestral haplotype. We observed a unique FMF haplotype common to Iraqi Jews, Arabs, and Armenians and two other haplotypes restricted to either the Iraqi Jewish or the Armenian population. These data support the view that a few major mutations account for a large percentage of the cases of FMF and suggest that some of these mutations arose before the affected Middle Eastern populations diverged from one another.

Familial Mediterranean fever (FMF) is an autosomal recessive disorder of unknown pathogenesis, characterized by recurrent, selflimited attacks of fever with synovitis, peritonitis, or pleurisy. Using DNAs from affected Israeli families, we have recently mapped the gene causing FMF (designated MEF) to the short arm of chromosome 16, with two-point lod scores in excess of 20. In this report we consider the possibility of a second FMF susceptibility locus. Before discovering linkage to markers on chromosome 16, we had found suggestive evidence for linkage to chromosome 17q, with the following maximal two-point lod scores: D17S74 (pCMM86), = 2.47, (= 0.20); D17S40 (pLEW101), = 2.15(= 0.15); D17S35 (CRI-pP3-1), = 1.78 (= 0.15); D17S46 (pLEW108), = 1.69 (= 0.18), D17S254, = 2.30 (= 0.20). Moreover, multipoint linkage analysis using D17S74 and D17S40 as fixed loci gave = 3.27 approximately 10 centimorgans (cM) telomeric to D17S40. Data with the chromosome 17 markers alone in our families suggested locus heterogeneity. Nevertheless, our families were not separable into complementary subsets showing linkage either to chromosome 16 or to chromosome 17. We also examined the possibility that the positive lod scores for chromosome 17 might reflect a secondary, modifying locus. By several measures of disease severity, families with positive lod scores for chromosome 17 loci had no worse disease than those with negative lod scores for these loci. We conclude that chromosome 17 does not encode a major FMF susceptibility gene for some of the families, nor does it encode a disease-modifying gene. Rather, it would appear that linkage to chromosome 17 is a “false positive” (type I) error. These results reemphasize the fact that a lod score of 3.0 corresponds to a posterior probability of linkage of 95%, with an attendant 1 in 20 chance of observing a false positive.

Cystinuria is an autosomal recessive disorder of amino acid transport. It is a common hereditary cause of kidney stones worldwide, and is associated with significant morbidity. In 17 affected families, we found linkage between cystinuria and three chromosome 2p markers. Maximal two–point lod scores between cystinuria and D2S119, D2S391 and D2S288 were 8.23 (θ=0.07), 3.73 (θ=0.15) and 3.03 (θ=0.12), respectively. Analysis of recombinants and multipoint linkage data indicated that the most likely order is cen–D2S391–D2S119–cystinuria–D2S177–tel. We also observed high rates of homozygosity for markers in this chromosomal region among 11 affected offspring of consanguineous marriages. Based on its map position and function, the recently cloned SLC3A1 amino acid transporter gene is a primary candidate gene for this disease.

TheSLC3A1gene encodes a transport protein for cystine and the dibasic amino acids. Recently mutations in this gene have been shown to cause cystinuria. We report the genomic structure and organization ofSLC3A1,which is composed of 10 exons and spans nearly 45 kb. Until now screening for mutations inSLC3A1has been based on RT-PCR amplification of illegitimate mRNA transcripts from white blood cells. In this report we provide primers for amplification of exons from genomic DNA, thus simplifying the process of screening forSLC3A1mutations in cystinuria.

Cystinuria is a genetic disease manifested by the development of kidney stones. In some patients, the disease is caused by mutations in the SLC3A1gene located on chromosome 2p. In others, the disease is caused by a gene that maps to chromosome 19q, but has not yet been cloned. Cystinuria is very common among Jews of Libyan ancestry living in Israel. Previously we have shown that the disease-causing gene in Libyan Jews maps to an 8-cM interval on chromosome 19q between the markers D19S409 and D19S208. Several markers from chromosome 19q showed strong linkage disequilibrium, and a specific haplotype was found in more than half of the carrier chromosomes. In this study we have analyzed Libyan Jewish cystinuria families with eight markers from within the interval containing the gene. Seven of these markers showed significant linkage disequilibrium. A common haplotype was found in 16 of the 17 carrier chromosomes. Analysis of historical recombinants placed the gene in a 1.8-Mb interval between the markers D19S430 and D19S874. Two segments of the historical carrier chromosome used to calculate the mutation's age revealed that the disease-causing mutation was introduced into this population 7–16 generations ago.

Nat. Immunol. 18, 832–842 (2017); published online 19 July 2017; corrected after print 17 August 2017 In the version of this article initially published, the final sentence of the third paragraph of the first subsection ('Monogenic periodic fever syndromes') incorrectly states that “Colchicine causes microtubule destabilization, thereby facilitating pyrin-inflammasome activation independently of RhoA.

ABSTRACT: Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of fever, synovitis, peritonitis, or pleurisy. Some patients eventually develop systemic amyloidosis. The biochemical cause of the disease is unknown. We have conducted a genome‐wide search for the FMF locus using 125 different DNA markers and mapped the FMF gene to the short arm of chromosome 16. The study was performed on 35 Israeli families primarily of North African and Iraqi origin. For the five markers D16S82 (p41‐1 Sacl), D16S80 (24‐1 Taq1), D16S84 (pCMM65 Taq1), D16S83 (pEKMDA2‐1 Rsal), and HBA (5′HVR Rsal) we obtained maximum lod scores of 2.72(θ = 0.08), 10.34 (θ = 0.04), 9.66 (θ = 0.050, 9.35 (θ = 0.03), and 14.31 (θ = 0.08), respectively. Multipoint analysis with HBA and D16S84 defined as a fixed loci gave a maximum lod score of 19.86 centromeric to D16S84. Crossovers defined by these markers place the FMF gene in an area of approximately 5 cM between D16S80 and D16S84. Other genes mapped to this area (16p13.3) include phosphodiesterase IB (PDE1B), hydroxyacyl‐glutathione hydrolase (HAGH), phosphoglycolate phosphatase (PGP), and the gene that causes adult polycystic kidney disease (PKD1). None of these genes bear an obvious pathophysiological relationship to FMF. Using additional markers from this region we hope to localize more precisely the FMF gene and to offer the possibility of prenatal diagnosis in selected cases. Our ultimate goal is to isolate and characterize the FMF gene.

The gene causing familial Mediterranean fever maps to the short arm of chromosome 16 in Druze and Moslem Arab families.

Reports on the identification of the gene for familial Mediterranean fever, by an international consortium of researchers, led by investigators at the National Institute of Arthritis and Musculosketal and Skin Diseases. Reference to the discovery of three different gene mutations that cause this inherited rheumatic disease; Effects of the discovery.