Neutrophil extracellular traps release in gout and pseudogout depends on the number of crystals regardless of leukocyte count.

OBJECTIVES: Microcrystal-induced arthritis is still an unresolved paradigm for medicine. Overt inflammation may be absent even when crystals occur in SF. Recently, the production of neutrophil extracellular traps (NETs) embedding MSU crystals has been proposed as a possible mechanism of the auto-resolution of the inflammatory phase during gout. We aimed to verify and quantify the release of NETs in SFs during gout and pseudogout attacks and to compare any differences with respect to crystals and neutrophils number, and to analyse activation of necroptosis pathway in SF from crystal-induced arthritis. METHODS: SF samples were obtained by arthrocentesis from 22 patients presenting acute crystal-induced arthritis, gout or pseudogout (n = 11 each group), and from 10 patients with acute non-crystal arthritis as controls. NETosis was quantified in SF by nucleic acid stain and by quantification of human neutrophil elastase. Activation of phosphorylated MLKL was assessed by western blot. RESULTS: We observed that SF neutrophils encountering MSU and CPPD crystals during episodes of gout and pseudogout release NETs in relation to the number of crystals in SF and irrespective of neutrophil density and type of crystal. This release was accompanied by necroptosis through the activation of the MLKL pathway. CONCLUSIONS: Our findings suggest that a role of NETs in crystal-induced arthritis is to 'trap extracellular particles', including microcrystals. Embedding crystals in aggregates of NETs may be the basis of tophi and CPPD deposition, and may have implications for disease evolution rather than for spontaneous resolution of the acute attack.

Hints for Genetic and Clinical Differentiation of Adult-Onset Monogenic Autoinflammatory Diseases.

Monogenic autoinflammatory diseases (mAIDs) are inherited errors of innate immunity characterized by systemic inflammation recurring with variable frequency and involving the skin, serosal membranes, synovial membranes, joints, the gastrointestinal tube, and/or the central nervous system, with reactive amyloidosis as a potential severe long-term consequence. Although individually uncommon, all mAIDs set up an emerging chapter of internal medicine: recent findings have modified our knowledge regarding mAID pathophysiology and clarified that protean inflammatory symptoms can be variably associated with periodic fevers, depicting multiple specific conditions which usually start in childhood, such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic syndrome, cryopyrin-associated periodic syndrome, and mevalonate kinase deficiency. There are no evidence-based studies to establish which potential genotype analysis is the most appropriate in adult patients with clinical phenotypes suggestive of mAIDs. This review discusses genetic and clinical hints for an ideal diagnostic approach to mAIDs in adult patients, as their early identification is essential to prompt effective treatment and improve quality of life, and also highlights the most recent developments in the diagnostic work-up for the most frequent hereditary periodic febrile syndromes worldwide.

Serum immunoglobulin D levels in patients with Behçet's disease according to different clinical manifestations.

OBJECTIVES: Behçet's disease (BD) is an autoinflammatory disorders mainly characterised by recurrent oral aphthosis, genital ulcers, and uveitis. The involvement of immunoglobulin D (IgD) in BD physiopathology is still unclear. The aim of our study was to assess the role of IgD in BD by comparing circulating levels of IgD in a cohort of BD patients and healthy controls (HC), as well as by correlating IgD levels with BD activity and different clinical presentations. METHODS: Serum IgD and SAA levels were analysed by ELISA assay in ninety-nine serum samples collected from 72 BD patients and in 29 HC subjects. RESULTS: Serum concentration of IgD were higher in BD patients compared with HC (p=0.029), in patients with high serum amyloid A (SAA) levels compared with patients with normal SAA levels (p=0.035), and among subjects with active mucocutaneous involvement compared with other patients (p=0.036). No correlations were identified between IgD serum levels and disease activity assessed by the BD current activity form (BDCAF) (p=0.640). No differences were observed in the IgD serum levels between patients with and without specific disease manifestations. Increased SAA levels (Odds Ratio = 3.978, CI: 1.356 -11.676) and active mucocutaneous BD manifestations (Odds Ratio = 4.286, CI: 1.192 - 15.407) were associated with a high risk for increased IgD serum levels. CONCLUSIONS: Serum IgD levels are significantly increased in BD patients, especially among patients with active mucocutaneous manifestations, suggesting a possible role of IgD in BD pathogenesis and in the onset of mucosal and skin lesions.

Critical regulation of Th17 cell differentiation by serum amyloid-A signalling in Behcet's disease.

The current understandings on cellular and molecular biology suggest that Th17 axis plays a pivotal role in Behcet's disease (BD) pathogenesis. Recently the role of serum amyloid-A (SAA) as a potential marker of disease activity in BD patients has been explored, and it has been reported that the occurrence of specific clinical features are significantly associated with high serum levels of this inflammatory mediator. The aim of this study was to investigate the cytokine-like activity of SAA in inducing Th17 differentiation from CD4 + T naive cells in BD. Purified peripheral monocytes from BD and healthy control (HC) were stimulated with SAA "in vitro", and secreted IL-8, TNF-α, IL-18, IFN-α, IFN-γ, IL-1ß and IL-6 were measured using a Bio-Rad multiplex cytokine immunoassay. To assess Th17 differentiation, purified CD4 + T cells were challenged with anti-CD3/CD28 antibodies, while cultured with supernatant derived from SAA stimulated monocytes, and intracellular staining of IL-17A and IFN-γ was evaluated by flow-cytometry. Furthermore, peripheral blood mononuclear cells (PBMCs) were stimulated with SAA and transcript levels of RAR-related orphan nuclear receptor (ROR)-γt and IL-17A were assessed by Real-time PCR. Upon stimulation with SAA, monocytes obtained from both HC and BD groups released large amounts of IL-8, IL-6, TNF-α, IL-1ß and IFN-α. Monocytes-derived supernatants from BD patients, but not HC, were capable of promoting Th17 but not Th1 differentiation from CD4 + T cells. However, SAA did not induce up-regulation of Th17 specific mRNA transcript such as IL-17A and (ROR)-γt in PBMCs from both HC and BD. In BD patients SAA induced Th17 polarization rather than Th1 differentiation from CD4 + T cells. These data suggest that a critical regulation of Th17 may be the functional link between acute SAA increase and the induction of Th17 mediated inflammatory response in BD.

Correlation of Serum Amyloid-A Levels, Clinical Manifestations, Treatment, and Disease Activity in Patients with Behçet's Disease.

BACKGROUND: Behçet's disease (BD) is an inflammatory disorder potentially leading to life- and sight-threatening complications. No laboratory marker correlating with disease activity or predicting the occurrence of disease manifestations is currently available. OBJECTIVES: To determine an association between serum amyloid-A (SAA) levels and disease activity via the BD Current Activity Form (BDCAF), to evaluate disease activity in relation to different SAA thresholds, to examine the association between single organ involvement and the overall major organ involvement with different SAA thresholds, and to assess the influence of biologic therapy on SAA levels. METHODS: We collected 95 serum samples from 64 BD patients. Related demographic, clinical, and therapeutic data were retrospectively gathered. RESULTS: No association was identified between SAA levels and BD disease activity (Spearman's rho = 0.085, P = 0.411). A significant difference was found in the mean BDCAF score between patients presenting with SAA levels < 200 mg/L and those with SAA levels > 200 mg/L (P = 0.027). SAA levels > 200 mg/L were associated with major organ involvement (P = 0.008). A significant association was found between SAA levels > 150 mg/dl and ocular (P = 0.008), skin (P = 0.002), and mucosal (P = 0.012) manifestations. Patients undergoing biologic therapies displayed more frequently SAA levels < 200 mg/L vs. patients who were not undergoing biologic therapies (P = 0.012). CONCLUSIONS: Although SAA level does not represent a biomarker for disease activity, it might be a predictor of major organ involvement and ocular disease relapse at certain thresholds in patients with BD.

Updated overview of molecular pathways involved in the most common monogenic autoinflammatory diseases.

An apparently unprovoked recurrent inflammation is the quintessential hallmark of autoinflammatory diseases (AIDs), a large and heterogeneous group of disorders in which there is poor regulation of the innate immune system with no clearly demonstrated autoimmune machinery involvement. Innate immunity pathways are diverse and our understanding of their molecular composition and function is continuously expanding. The impaired immune responses we observe in monogenic AIDs, mostly in the hereditary periodic fever syndromes, is officiated by target molecules of microbial origin (pathogen-associated molecular patterns) and also host molecules (danger-associated molecular patterns). Further crucial components of innate immune mechanisms that contribute differently in the deregulated inflammatory patterns of different AIDs include Toll-like receptors, Nod-like receptors, scaffolding proteins (such as the caspase recruitment domain of proteins), cytosolic DNA-sensing molecules, inflammatory multi-protein complexes (referred to as inflammasomes), complement system, and others. In recent years, the knowledge of protean molecular pathways responsible for the most common monogenic AIDs has expanded, in parallel with very recent extraordinary technological advances, allowing the identification and characterisation of some unknown aspects of the innate immunity. This review will list and describe the most common monogenic febrile syndromes belonging to AIDs and will focus on current insights dealing with their pathologic processes.

IL-6 blockade in the management of non-infectious uveitis.

Several pathogenetic studies have paved the way for a newer more rational therapeutic approach to non-infectious uveitis, and treatment of different forms of immune-driven uveitis has drastically evolved in recent years after the advent of biotechnological drugs. Tumor necrosis factor-α targeted therapies, the first-line recommended biologics in uveitis, have certainly led to remarkable results in patients with non-infectious uveitis. Nevertheless, the decision-making process turns out to be extremely difficult in anti-tumor necrosis factor or multidrug-resistant cases. Interleukin (IL)-6 holds a critical role in the pathogenic pathways of uveitis, due to its extended and protean range of effects. On this background, manipulation of IL-6 inflammatory cascade has unraveled encouraging outcomes. For instance, rising evidence has been achieved regarding the successful use of tocilizumab, the humanized monoclonal antibody targeted against the IL-6 receptor, in treating uveitis related to juvenile idiopathic arthritis or Behçet's disease. Similar findings have also been reported for uveitis associated with systemic disorders, such as rheumatoid arthritis or multicentric Castleman disease, but also for idiopathic uveitis, the rare birdshot chorioretinopathy, and even in cases complicated by macular edema. This work provides a digest of all current experiences and evidences concerning IL-6 blockade, as suggested by the medical literature, proving its potential role in the management of non-infectious uveitis.

Cytokine Signatures in Mucocutaneous and Ocular Behçet's Disease.

Behçet's disease (BD) is a multi-systemic inflammatory disorder consisting of recurrent oral aphthosis, genital ulcers, and chronic relapsing bilateral uveitis; however, many other organs may be affected. Several pro-inflammatory cytokines, mainly derived from Th1 and Th17 lymphocytes, seem to be involved in different pathogenic pathways leading to development of the clinical manifestations. On this basis, the primary aim of our study was to compare a core set of pro-inflammatory cytokines between patients with BD and healthy control (HC). The secondary goal was to evaluate potential correlations between these putative circulating biomarkers, the status of disease activity, and the specific organ involvement at the time of sample collection. Fifty-four serum samples were collected from 46 BD patients (17 males, 29 females, mean age 45.5 ± 11.3 years), and 19 HC (10 males, 9 females, mean age 43 ± 8.3 years). Twenty-five serum cytokines (APRIL/TNFS13, BAFF/TNFSF13B, sCD30/TNFRSF8, sCD163, Chitinase3-like1, gp130/sIL-6Rb, IFNb, sIL-6Ra, IL-10, IL-11, IL-19, IL-20, IL-26, IL-27 (p28), IL-28A/IFN-lambda2, IL-29/IFN-lambda1, IL-32, IL-34, IL-35, LIGHT/TNFSF-14, Pentraxin-3, sTNF-R1, sTNF-R2, TSLP, and TWEAK/TNFSF-12) were simultaneously quantified using a Bio-Rad cytokine bead arrays. Serum concentration of sTNF-R1 (p < 0.01) and sTNF-R2 (p < 0.01) resulted higher in both active and inactive BD than HC, while Chitinase3-like1 (p < 0.05) and gp130/sIL-6Rb (p < 0.01) serum levels were significantly higher in inactive BD, and IL-26 (p < 0.01) in active BD than HC. No differences were observed between inactive and active BD group. In addition, we observed that gp130/sIL-6Rb, sIL-6Ra, IL-35, and TSLP serum levels were significantly enhanced in patients with mucocutaneous manifestations plus ocular involvement (MO-BD) compared to subgroup with only mucocutaneous involvement (M-BD). Our findings may suggest a signature of IL-6, tumor necrosis factor-α as well as of Th17 response in BD patients due to increased levels of gp130/sIL-6Rb, sTNF-R1, sTNF-R2, IL-26, respectively. This evidence could contribute to improve the knowledge regarding the role of these citokines in the induction of specific BD clinical features.

The diagnostic evaluation of patients with a suspected hereditary periodic fever syndrome: experience from a referral center in Italy.

The study aims are to describe the activity of our Unit on the diagnostics of monogenic autoinflammatory diseases (AIDs), and to apply the clinical classification criteria for periodic fevers from the Eurofever Registry to our cohort of patients, thus evaluating their usefulness in the real life. We retrospectively analyzed data from patients referring to our Center for recurrent fever attacks, and undergoing genetic analysis between April 2014 and July 2016, and we applied the classification criteria to both genetically positive and -negative patients. We visited 195 patients (101 females, 94 males); 126 (64.6%) were adults and 192 (98.5%) Caucasians; 12.3% carried mutations and 12.7% of adults were genetically positive. No statistically significant differences were identified in the frequency of genetic diagnosis between adults and children (p = 0.82) as well as in the frequency of genetic diagnosis, based on the number of genes evaluated (p = 0.57). When we applied the Eurofever criteria, 126/195 (64.6%) patients were classified for at least one among the four main monogenic AIDs; 22 (11.3%) patients fulfilled criteria for 2 diseases and 4 (2.1%) for 3 diseases. Among patients carrying mutations, 12/24 (50%) correctly fulfilled the score, 3/24 (12.5%) fulfilled criteria differently from their genetic diagnosis; 9/22 (40.9%) recieved no classification. An expanded genetic testing does not seem useful, while a correct interpretation of patients' clinical picture may allow performing specific genetic testing. The classification criteria from the Eurofever Registry have shown to be a beneficial tool in the evaluation of patients with a suspected monogenic AID.

Clinical Characteristics of Patients Carrying the Q703K Variant of the NLRP3 Gene: A 10-year Multicentric National Study.

OBJECTIVE: The aim of our study was to analyze the clinical and functional effect of the p.Q703K (p. Q705K, c. 2107C>A) variant of the NLRP3 gene in a population of patients screened for suspected cryopyrin-associated periodic syndrome (CAPS). METHODS: Since 2002, 580 patients underwent molecular analysis for NLRP3. Data on clinical presentation, response to treatment, and longterm followup were collected using a uniform questionnaire. The pattern of cytokine secretion after lipopolysaccharide stimulation from isolated monocytes was analyzed in 3 patients carrying the p.Q703K variant and 1 patient with a chronic infantile neurologic, cutaneous, articular syndrome phenotype carrying both the p.M406I and p.Q703K, and compared with 7 patients with CAPS with sure pathogenic variants and 6 healthy controls. RESULTS: The p.Q703K variant was found in 57 screened patients with an overall allelic frequency of 5%. The frequency in normal controls was 5.5%. Clinical data at the moment of molecular analysis and at followup were available in 36 patients. Two patients displayed additional mutations of NLRP3. The mean followup was 2.5 years. Thirteen patients (39%) had a final diagnosis different from the original suspicion of CAPS. The remaining 21 patients displayed a mild phenotype mainly characterized by recurrent episodes of urticarial rash and arthralgia. Only 8 patients were treated with anti-interleukin (IL)-1 treatment, with a complete response in 5 patients. The pattern of secretion of IL-1ß and other cytokines (IL-6 and IL-1 receptor antagonist) in patients did not display the aberrancies observed in patients with CAPS and was similar to that observed in healthy controls. CONCLUSION: The present study confirms the weak clinical and functional effect of the p.Q703K variant.

Differential impact of high and low penetrance TNFRSF1A gene mutations on conventional and regulatory CD4+ T cell functions in TNFR1-associated periodic syndrome.

TNFR-associated periodic syndrome is an autoinflammatory disorder caused by autosomal-dominant mutations in TNFRSF1A, the gene encoding for TNFR superfamily 1A. The lack of knowledge in the field of TNFR-associated periodic syndrome biology is clear, particularly in the context of control of immune self-tolerance. We investigated how TNF-α/TNFR superfamily 1A signaling can affect T cell biology, focusing on conventional CD4(+)CD25(-) and regulatory CD4(+)CD25(+) T cell functions in patients with TNFR-associated periodic syndrome carrying either high or low penetrance TNFRSF1A mutations. Specifically, we observed that in high penetrance TNFR-associated periodic syndrome, at the molecular level, these alterations were secondary to a hyperactivation of the ERK1/2, STAT1/3/5, mammalian target of rapamycin, and NF-κB pathways in conventional T cells. In addition, these patients had a lower frequency of peripheral regulatory T cells, which also displayed a defective suppressive phenotype. These alterations were partially found in low penetrance TNFR-associated periodic syndrome, suggesting a specific link between the penetrance of the TNFRSF1A mutation and the observed T cell phenotype. Taken together, our data envision a novel role for adaptive immunity in the pathogenesis of TNFR-associated periodic syndrome involving both CD4(+) conventional T cells and Tregs, suggesting a novel mechanism of inflammation in the context of autoinflammatory disorders.

Putative Role of Serum Amyloid-A and Proinflammatory Cytokines as Biomarkers for Behcet's Disease.

Behcet's disease (BD) is a multisystemic disorder of unknown etiology characterized by relapsing oral-genital ulcers, uveitis, and involvement of vascular, gastrointestinal, neurological, and musculoskeletal system. Although disease pathogenesis is still unclear, both innate and adaptive immunity have shown to play a pivotal role, and multiple proinflammatory cytokines seem to be involved in different pathogenic pathways that eventually lead to tissue damage.The aims of our study were to evaluate serum cytokines levels of IL-8, IL-18, IFN-α2a, IL-6, IFN-γ, CXCL10, CXCL11, CXCL9, and SAA levels in patients with BD, in comparison to healthy controls (HC), and to correlate their levels to disease activity.We included 78 serum samples obtained from 58 BD patients and analyzed a set of proinflammatory cytokines including IL-8, IL-18, IFN-α2a, IL-6, IFN-γ, CXCL10, CXCL11, and CXCL9 by multiplex bead analysis as well as SAA by enzyme-linked immunosorbent assay.Compared to HC, BD patients showed elevated cytokine levels of IL-8, IL-18, IFN-α2a, and IL-6, and low levels of CXCL11. BD patients with SAA serum levels >20 mg/L showed higher levels of proinflammatory markers than HC or group with SAA ≤20 mg/L. IL-18, IFN-α2a, and IL-6 were higher in BD group with SAA >20 mg/L than HC, while IL-8 and CXCL9 levels were higher than in patients with SAA ≤20 mg/L and HC.Active BD patients with SAA >20 mg/L exhibited elevated levels of inflammatory mediators, suggesting that may exist a relationship between SAA and proinflammatory cytokines in the intricate scenario of BD pathogenesis.

Possible chondroprotective effect of canakinumab: an in vitro study on human osteoarthritic chondrocytes.

Canakinumab is a human IgGκ monoclonal antibody that neutralizes the activity of interleukin (IL)-1ß blocking interaction with IL-1ß receptors. Our study aimed to evaluate the in vitro effect of canakinumab on human osteoarthritic (OA) chondrocytes cultivated in the presence or absence of tumor necrosis factor (TNF)-α. Articular cartilage was obtained from the femoral heads of patients with osteoarthritis (OA). Chondrocytes were incubated with two concentrations (1µg/ml and 10µg/ml) of canakinumab alone or with TNF-α (10ng/ml) for 48h. We evaluated cell viability, release of proteoglycans (PG) and nitric oxide (NO) in culture medium, inducible nitric oxide synthase (iNOS) and metalloproteinanes (MMP)-1,3,13 gene expression, apoptosis, necrosis and morphological feature by transmission electron microscopy (TEM). Canakinumab alone did not have cytotoxic effect. Cell viability was reduced significantly (p<0.001) by TNF-α and restored by canakinumab at both concentrations used. TNF-α determined a significant decrease of PG (p<0.001) and an increase of NO (p<0.001) and MMP-1,3,13 gene expression. Canakinumab significantly increased the PG levels and decreased (1µg/ml, p<0.01; 10µg/ml, p<0.01) NO levels in cells cultured with TNF-α. The NO data were confirmed by the immunocytochemistry assay for iNOS. A significant reduction of MMP-1,3,13 gene expression was induced by canakinumab. Our experiments confirmed the pro-apoptotic effect of TNF-α and demonstrated a protective role of canakinumab. The results concerning biochemical data were further confirmed by the morphological findings obtained by TEM. We showed that canakinumab counteracts the negative effects of TNF-α on OA chondrocyte cultures and may have a potential chondroprotective role in OA.

Early-onset sarcoidosis caused by a rare CARD15/NOD2 de novo mutation and responsive to infliximab: a case report with long-term follow-up and review of the literature.

Granulomatous autoinflammatory diseases are monogenic syndromes caused by mutations in the region encoding for the nucleotide-binding domain region of the NOD2/CARD15 gene with subsequent dysregulation of the inflammatory response and formation of noncaseous granulomas. They include Blau syndrome (BS) and early-onset sarcoidosis (EOS); both are clinically and genetically indistinguishable between them and they are the familial (autosomal dominantly inherited) and sporadic forms of the same disease, respectively. We describe a case of EOS, misdiagnosed for 30 years such as "juvenile rheumatoid arthritis" before and "classic sarcoidosis" later. In our patient, we found a new de novo mutation (E383G) in NOD2 that has been reported only in a family of Japanese patients with BS. After long-term follow-up (42 months), infliximab maintained good efficacy and safety without any sign of disease relapse and side effects.

Anakinra treatment in drug-resistant Behcet's disease: a case series.

The study objective was to report treatment with an interleukin (IL)-1 receptor antagonist, anakinra, in patients with multiorgan Behcet's disease (BD). Comparison of clinical manifestations, previous treatments, markers of inflammation, concomitant medications, treatment regimen modifications, relapses, and adverse events before and during anakinra administration among patients with BD were evaluated. Nine BD patients (mean age 34.55 ± 16.30 years) refractory to tumor necrosis factor blockers and standardized therapies are reported in our survey. Their mean age at disease onset was 25 ± 13.88 years and their overall disease duration was 9.55 ± 5.33 years. All patients were positive for the HLA-B51 allele. Within 1 or 2 weeks following the initiation of anakinra, eight out of nine patients promptly responded, and most of them were maintained on 100 mg of daily anakinra with low doses of prednisone. However, most patients experienced a relapse in one or more clinical manifestations over time (mean time to relapse 29 ± 21.65 weeks), and only one patient remained completely under control on anakinra monotherapy. Despite a relapse in one or more disease manifestations, treatment was continued in most patients for a mean period of 13.75 ± 6.49 months. No serious adverse events occurred. Eight out of nine refractory BD patients showed a prompt improvement after starting anakinra, supporting the concept that IL-1 plays a pathological role in this disease. Nevertheless, after several months, most patients experienced a relapse. It remains unclear whether increasing the dose of anakinra would have prevented the reoccurrence of disease activity.

Paradoxical mucocutaneous flare in a case of Behçet's disease treated with tocilizumab.

We report on a patient with a long-standing history of recurrent oral aphthosis and pseudofolliculitis, diagnosed with Behçet's disease (BD), previously treated with high-dose prednisone, colchicine, cyclosporine, cyclophosphamide and methotrexate, all of which were partially effective. Treatment with the chimeric mouse-human anti-tumour necrosis factor (TNF)-α monoclonal antibody infliximab brought about the resolution of mucocutaneous lesions for a period of 6 years. After an oral and articular BD relapse, the anti-interleukin-6 agent tocilizumab was started in association with high-dose prednisone. Unexpectedly, the patient experienced a paradoxical mucocutaneous flare following tocilizumab administration, which worsened after the second infusion. Tocilizumab was then discontinued, and total recovery was achieved after the patient was started on the fully human anti-TNF-α monoclonal antibody golimumab in association with colchicine and methylprednisolone.

The labyrinth of autoinflammatory disorders: a snapshot on the activity of a third-level center in Italy.

Autoinflammatory disorders (AIDs) are a novel class of diseases elicited by mutations in genes regulating the homeostasis of innate immune complexes, named inflammasomes, which lead to uncontrolled oversecretion of the proinflammatory cytokine interleukin-1ß. Protean inflammatory symptoms are variably associated with periodic fever, depicting multiple specific conditions. Childhood is usually the lifetime in which most hereditary AIDs start, though still a relevant number of patients may experience a delayed disease onset and receive a definite diagnosis during adulthood. As a major referral laboratory for patients with recurrent fevers, we have tested samples from 787 patients in the period September 2007-March 2014, with a total of 1,328 AID-related genes evaluated and a gene/patient ratio of 1.69. In this report, we describe our experience in the clinical approach to AIDs, highlight the most striking differences between child and adult-onset AIDs, and shed an eye-opening insight into their diagnostic process.