Dermatologic Features of ADA2 Deficiency in Cutaneous Polyarteritis Nodosa

A case with febrile attacks and vasculopathy associated with ADA2 and MEFV pathogenic variants

Deficiency of adenosine deaminase 2 (DADA2), caused by recessive mutations in the adenosine deaminase 2 (ADA2) gene, results in cutaneous or systemic vasculitis with variable clinical manifestations. There is only one other case in literature carrying both ADA2 and MEFV gene pathogenic variants. Here we report the second case that carries both ADA2 and MEFV pathogenic variants, presenting with characteristic phenotypes of both familial Mediterranean fever (FMF) and DADA2. A male patient, currently 29 years old, was initially diagnosed with FMF and developed livedo reticularis and nodular dermal lesions compatible with cutaneous polyarteritis nodosa (PAN) a year after diagnosis. His family history revealed a brother 2 years older than himself who was diagnosed with PAN and died at age 22 because of gut perforation secondary to acute mesenteric ischaemia. ADA2 gene mutation analysis on chromosome 22q11.1 was positive, and the patient responded to colchicine and infliximab.

Cutaneous polyarteritis nodosa and pulmonary arterial hypertension: An unexpected liaison. A case report

BACKGROUND

Cutaneous polyarteritis nodosa (cPAN) is a form of medium-sized vessel necrotizing vasculitis. It is a rare, skin-limited variant of polyarteritis nodosa, characterized by dermal and subcutaneous tissue involvement. The most common findings in cPAN include digital gangrene, livedo reticularis, and tender subcutaneous nodules. However, while limited to the skin, cPAN results in significant morbidity and mortality due to the accompanying skin ischemia and necrosis, such that patients are vulnerable to superinfection. Here, we describe a unique presentation of cPAN associated with pulmonary arterial hypertension (PAH).

METHODS

A 78-year-old female presented with digital ischemia and leg ulcers associated with PAH. Skin biopsy showed necrotizing fibrinoid necrosis of the small- and middle-sized vessels of the dermis. A diagnosis of cPAN and PAH was made. The patient was treated with glucocorticoids, vasodilators, and cyclophosphamide.

RESULTS

She died due to severe sepsis complications.

CONCLUSION

To date, this is the first case report describing the association between cPAN and PAH. In this case, PAH is a complication of the cutaneous vasculitides suggesting that vasculopathy could play a role in the pathophysiology of PAH. However, the underlying pathophysiological mechanisms still have to be firmly established.

Deficiency of Adenosine Deaminase 2: Clinical Manifestations, Diagnosis, and Treatment

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic vasculitis syndrome caused by biallelic mutations in the adenosine deaminase 2 gene. The diagnosis of DADA2 is confirmed by decreased enzymatic activity of ADA2 and genetic testing. Symptoms range from cutaneous vasculitis and polyarteritis nodosa-like lesions to stroke. The vasculopathy of DADA2 can affect many organ systems, including the gastrointestinal and renal systems. Hematologic manifestations occur early with hypogammaglobulinemia, lymphopenia, pure red cell aplasia, or pancytopenia. Treatment can be challenging. Tumor necrosis factor inhibitors are helpful to control inflammatory symptoms. Hematopoietic stem cell transplant may be needed to treat refractory cytopenias, vasculopathy, or immunodeficiency.

A wide spectrum of phenotype of deficiency of deaminase 2 (DADA2): a systematic literature review

INTRODUCTION

Deficiency of adenosine deaminase 2 (DADA2) is a rare monogenic autoinflammatory disease, whose clinical phenotype was expanded since the first cases, originally described as mimicker of polyarteritis nodosa, with immunodeficiency and early-onset stroke.

METHODS

A systematic review according to PRISMA approach, including all articles published before the 31st of August 2021 in Pubmed and EMBASE database was performed.

RESULTS

The search identified 90 publications describing 378 unique patients (55.8% male). To date 95unique mutations have been reported. The mean age at disease onset was 92.15 months (range 0-720 months), 32 (8.5%) showed an onset of the first signs/symptoms after 18 years old and 96 (25.4%) after 10 years old. The most frequent clinical characteristics described were cutaneous (67.9%), haematological manifestations (56.3%), recurrent fever (51.3%), neurological as stroke and polyneuropathy (51%), immunological abnormalities (42.3%), arthralgia/arthritis (35.4%), splenomegaly (30.6%), abdominal involvement (29.8%), hepatomegaly (23.5%), recurrent infections (18.5%), myalgia (17.9%), kidney involvement (17.7%) etc. Patients with skin manifestations were older than the others (101.1 months SD ± 116.5, vs. 75.3 SD ± 88.2, p 0.041), while those with a haematological involvement (64.1 months SD ± 75.6 vs. 133.1 SD ± 133.1, p < 0.001) and immunological involvement (73.03 months SD ± 96.9 vs. 103.2 SD ± 112.9, p 0.05) are younger than the others. We observed different correlations among the different clinical manifestations. The use of anti-TNFα and hematopoietic cell stems transplantation (HCST) has improved the current history of the disease.

CONCLUSION

Due to this highly variable phenotype and age of presentation, patients with DADA2 may present to several type of specialists. Given the important morbidity and mortality, early diagnosis and treatment are mandatory.

A comprehensive review on pathogenesis, associations, clinical findings, and treatment of livedoid vasculopathy

Livedoid vasculopathy (LV) is a thrombo-occlusive vasculopathy that involves the dermal vessels. Clinically, it is characterized by the presence of painful purpuric ulcers on the lower extremities. Histopathologically, it shows intraluminal fibrin deposition and thrombosis, segmental hyalinization, and endothelial proliferation. It is important to notice that the term "atrophie blanche" is descriptive and it includes not only patients with LV but also patients with a combination of vasculitis and vasculopathy, that is, LV and medium-sized vasculitis such as cutaneous polyarteritis nodosa (PANc). Diagnosis is based on a proper clinicopathological correlation, excluding the main differential diagnosis and considering vasculitis as a mimicker or concomitant diagnosis. Coagulation disorders must also be studied although they are not found in all LV. Its frequency is reviewed as well. Treatment of LV is challenging, and different therapies have been attempted. Among them, pain management, wound care, control of cardiovascular risk factors, and both antiplatelets and anticoagulants, mostly rivaroxaban, are the main therapies used. These different therapies as well as their degree of evidence are reviewed.

Recent topics related to etiology and clinical manifestations of cutaneous arteritis

Cutaneous polyarteritis nodosa (cPAN) was first reported by Lindberg in 1931. It has been recognized as a skin-limited vasculitis whose cutaneous histopathological features are indistinguishable from those of PAN. Cutaneous arteritis (CA) was defined as a form of single-organ vasculitis in the revised Chapel Hill Classification and was recognized as the same disease as cPAN. It became known that deficiency of adenosine deaminase 2 (DADA2) cases were included in cases that had been diagnosed with CA. Because of their similarity and differences in the treatment methods, DADA2 should be considered in CA cases, especially if they are diagnosed or developed in early childhood. Cutaneous arteritis may be classified as an immune complex-mediated vasculitis. It was reported that the pathogenesis of anti-lysosomal-associated membrane protein-2 (LAMP-2) antibodies and anti-phosphatidylserine-prothrombin complex (PS/PT) antibodies as good parameters in CA. The main skin manifestations include livedo racemosa, subcutaneous nodules, and ulcers. Although CA is recognized to have a benign clinical course, it has become known that it is easy to relapse. The existence of skin ulcers upon diagnosis or sensory neuropathies was suggested to be a predictor of poor prognosis. Cutaneous arteritis with them may need to be treated with more intensive therapies.

ELISA based assays to measure adenosine deaminases concentration in serum and saliva for the diagnosis of ADA2 deficiency and cancer

Adenosine deaminases (ADAs) are enzymes of purine metabolism converting adenosine to inosine. There are two types of ADAs in humans ADA1 and ADA2. While both ADA1 and ADA2 share the same substrate, they differ in expression, cellular localization, and catalytic properties. The genetic deficiency of ADA1 results in severe combined immunodeficiency (SCID), while lack in ADA2 (DADA2) results in multiple phenotypes ranging from systemic inflammation to vascular pathology. Clinical studies have shown that the levels of ADAs in biological fluids are altered in pathophysiological conditions, suggesting that ADA activity could be a convenient marker for the diagnosis of immune diseases and cancer. Here, we describe sensitive and straightforward ELISA assays to measure ADA1 and ADA2 concentrations in biological fluids. Analysis of the serum and saliva samples from the healthy controls and DADA2 patients revealed that ADA2 enzyme concentration is significantly lower in patients than in healthy controls. In contrast, the concentration of ADA2 increases in the serum of patients with large granular leukocyte leukemia (LGLL) and patients’ saliva with head and neck cancer. Thus, this simple, non-invasive method allows for distinguishing healthy controls from the affected patient. It can be implemented in screening and diagnosis of DADA2 and follow up the treatment of LGLL and several types of head and neck cancer.

Evaluation of subclinical ocular involvement in patients with deficiency of adenosine deaminase 2 (DADA2)

PURPOSE

To evaluate changes in the peripapillary, macular, and choroidal microvasculature in the eyes of patients with deficiency of adenosine deaminase 2 (DADA2) and no clinical signs of ocular involvement.

METHODS

The study included 12 eyes of 12 patients with DADA2 and 24 eyes of 24 healthy subjects. The foveal avascular zone (FAZ), macular vessel densities (VDs) in the superficial and deep retinal capillary plexuses, peripapillary VDs, and choroidal thickness were evaluated by optical coherence tomography angiography (OCTA). Measurements were compared between DADA2 patients and healthy controls.

RESULTS

The median age was 17 (8-25) years in DADA2 patients and 17.5 (7-23) years in control group at the OCTA visit (p = 0.934). FAZ area did not differ between the groups (p = 0.224). In the superficial capillary plexus, whole-image, foveal, and parafoveal VD values were slightly lower in DADA2 patients than in controls (p = 0.054, p = 0.052, p = 0.117). In the deep capillary plexus, whole-image and parafoveal VD values were significantly lower in DADA2 patients than controls (p = 0.010, p = 0.001). VD in the radial peripapillary capillary plexus was also lower in DADA2 patients, with significantly lower peripapillary VD (p = 0.002). Subfoveal choroidal thickness was significantly higher in patients with DADA2 (p < 0.001).

CONCLUSIONS

This OCTA study demonstrates that both retinal and choroidal involvement may occur in DADA2 patients before the emergence of evident clinical findings.

Mechanisms of vascular inflammation in deficiency of adenosine deaminase 2 (DADA2)

Deficiency of adenosine deaminase 2 (DADA2) was first described as a monogenic form of systemic vasculitis that closely resembles polyarteritis nodosa (PAN). The phenotypic spectrum of DADA2 has vastly expanded in recent years and now includes pure red cell aplasia, bone marrow failure syndrome, lymphoproliferative disease, and humoral immunodeficiency. Vasculitis remains the most common presentation of DADA2, and treatment with tumor necrosis factor inhibitors (TNFi) has shown remarkable efficacy in preventing stroke and ameliorating features of systemic inflammation. The precise function of ADA2 has not been elucidated, and how absence of ADA2 ignites inflammation is an active area of research. In this review, we will discuss the current understanding of DADA2 from research and clinical perspectives. We will evaluate several proposed functions of ADA2, including polarization of monocyte phenotype, regulation of neutrophil extracellular trap formation, and modulation of innate immunity. We will also review the role of inflammatory cytokines including TNF and type I interferons. Lastly, we will provide future perspectives on understanding the phenotypic heterogeneity of DADA2 and discuss potential treatment options.

Fatal Coronary Artery Vasculitis With Mixed Features

ABSTRACT

Atherosclerotic cardiovascular disease (ASCVD) is often investigated by medical examiners as a cause of sudden death. Because of the variation in presentation of atherosclerotic cardiovascular disease, the examiner must be cautious when assigning a final diagnosis. The presented case depended upon histologic examination of coronary artery lesions to reach an appropriate final diagnosis of vasculitis with mixed features. Autopsy findings showed hepatosplenic vasculitis with noncaseating granulomas, and multifocal diffuse coronary fibrosis with histologic findings consistent with late-stage polyarteritis nodosa (PAN). However, the patient lacked the hallmark renal involvement observed in PAN. Furthermore, the vasculitis within the liver showed a highly granulomatous appearance, more consistent with IgG4 disease. In these mixed-appearance cases with limited history, exact categorization of the disease may prove difficult to impossible. Herein, we review a differential diagnosis of classic vasculitides with a focus on those that commonly affect the coronary arteries in adults, namely, PAN.

Localized Forms of Vasculitis

Purpose of Review

To provide an updated review on epidemiology, clinical manifestations, diagnostic assessment, treatment, and prognosis of localized vasculitis, following the 2012 Revised International Chapel Hill Consensus Conference Nomenclature on single-organ vasculitis.

Recent Findings

Localized, single-organ vasculitides encompass a group of rare conditions in which there is no evidence of concomitant systemic vasculitis. Most data on this topic derives from case reports and small case series. Although some aspects of these diseases, such as clinical manifestations and histologic findings, have already been extensively investigated, there is still a lack of robust data concerning the pathogenesis, epidemiology, and treatment.

Summary

Localized vasculitides may have a wide range of clinical features depending on the organ affected. The inflammatory process may have a multifocal/diffuse or unifocal distribution. Diagnosis is usually based on histopathology findings and exclusion of systemic vasculitis, which may frequently pose a challenge. Further research on treatment is warranted.

Histologic Patterns and Clues to Autoinflammatory Diseases in Children: What a Cutaneous Biopsy Can Tell Us

Autoinflammation is defined by aberrant, antigen-independent activation of the innate immune signaling pathways. This leads to increased, pro-inflammatory cytokine expression and subsequent inflammation. In contrast, autoimmune and allergic diseases are antigen-directed immune responses from activation of the adaptive immune system. The innate and adaptive immune signaling pathways are closely interconnected. The group of 'complex multigenic diseases' are a result of mutual dysregulation of both the autoinflammatory and autoimmune physiologic components. In contrast, monogenic autoinflammatory syndromes (MAIS) result from single mutations and are exclusively autoinflammatory in their pathogenesis. Studying the clinical and histopathological findings for the various MAIS explains the phenotypical correlates of their specific mutations. This review aims to group the histopathologic clues for autoinflammation into three recognizable patterns. The presence of these histologic patterns in a pediatric patient with recurrent fevers and systemic inflammation should raise suspicion of an autoinflammatory component in MAIS, or, more frequently, in a complex multigenic disease. The three major histopathological patterns seen in autoinflammation are as follows: (i) the 'neutrophilic' pattern, seen in urticarial neutrophilic dermatosis, pustular psoriasis, aseptic neutrophilic folliculitis, and Sweet's syndrome; (ii) the 'vasculitic' pattern seen in small vessel-vasculitis (including hypersensitivity/leukocytoclastic vasculitis, thrombosing microangiopathy and lymphocytic vasculitis), and intermediate-sized vessel vasculitis, mimicking polyarteritis nodosa; and (iii) the 'granulomatous' pattern. Beyond these three patterns, there are additional histopathologic clues, which are detailed below. It is important for a dermatopathologist to recognize the patterns of autoinflammation, so that a diagnosis of MAIS or complex multigenic diseases may be obtained. Finally, careful histopathologic analyses could contribute to a better understanding of the various clinical manifestations of autoinflammation.

Plasma Adenosine Deaminase (ADA)-1 and -2 Demonstrate Robust Ontogeny Across the First Four Months of Human Life

Background

Human adenosine deaminases (ADAs) modulate the immune response: ADA1 via metabolizing adenosine, a purine metabolite that inhibits pro-inflammatory and Th1 cytokine production, and the multi-functional ADA2, by enhancing T-cell proliferation and monocyte differentiation. Newborns are relatively deficient in ADA1 resulting in elevated plasma adenosine concentrations and a Th2/anti-inflammatory bias compared to adults. Despite the growing recognition of the role of ADAs in immune regulation, little is known about the ontogeny of ADA concentrations.

Methods

In a subgroup of the EPIC002-study, clinical data and plasma samples were collected from 540 Gambian infants at four time-points: day of birth; first week of life; one month of age; and four months of age. Concentrations of total extracellular ADA, ADA1, and ADA2 were measured by chromogenic assay and evaluated in relation to clinical data. Plasma cytokines/chemokine were measured across the first week of life and correlated to ADA concentrations.

Results

ADA2 demonstrated a steady rise across the first months of life, while ADA1 concentration significantly decreased 0.79-fold across the first week then increased 1.4-fold by four months of life. Males demonstrated significantly higher concentrations of ADA2 (1.1-fold) than females at four months; newborns with early-term (37 to <39 weeks) and late-term (≥41 weeks) gestational age demonstrated significantly higher ADA1 at birth (1.1-fold), and those born to mothers with advanced maternal age (≥35 years) had lower plasma concentrations of ADA2 at one month (0.93-fold). Plasma ADA1 concentrations were positively correlated with plasma CXCL8 during the first week of life, while ADA2 concentrations correlated positively with TNFα, IFNγ and CXCL10, and negatively with IL-6 and CXCL8.

Conclusions

The ratio of plasma ADA2/ADA1 concentration increased during the first week of life, after which both ADA1 and ADA2 increased across the first four months of life suggesting a gradual development of Th1/Th2 balanced immunity. Furthermore, ADA1 and ADA2 were positively correlated with cytokines/chemokines during the first week of life. Overall, ADA isoforms demonstrate robust ontogeny in newborns and infants but further mechanistic studies are needed to clarify their roles in early life immune development and the correlations with sex, gestational age, and maternal age that were observed.

The role of vascular inflammation markers in deficiency of adenosine deaminase 2

OBJECTIVES

The first objective was to assess the role of vascular inflammatory factors in the pathogenesis of deficiency of adenosine deaminase 2 (DADA2) and to compare these markers among DADA2 patients with different phenotypes. We also aimed to investigate differences between DADA2 patients with vasculitic features and classic polyarteritis nodosa (PAN) for the aforementioned markers.

METHODS

The study included eighteen DADA2 patients, ten PAN patients, and eight healthy controls. Plasma levels of sST2, sRAGE, Tie-2, sCD40L, Tie-1, sFlt-1, LIGHT, TNF-α, PlGF, IL-6, IL-18, IL-10, MCP-1 were studied by cytometric bead-based multiplex assay panel.

RESULTS

Among the DADA2 patients, five had hematological manifestations, 13 had vasculitic findings, and accompanying immunological findings were present in seven patients. Nine patients had neurological findings, five of whom had neuropathy. Plasma levels of Tie-1 and sFlt-1 were higher in the overall DADA2 patients compared to healthy controls and PAN patients (p<0.001 and p = 0.004, respectively). DADA2 patients with PAN-like features had higher sRAGE, Tie-2, and TNF-α levels compared to PAN patients (p = 0.013, p = 0.003, and p = 0.001, respectively). In DADA2 patients with hematological findings, plasma IL-18 levels were higher than those with PAN-like phenotype (p = 0.001). Finally, DADA2 patients with neuropathy had higher sRAGE concentrations than patients without neuropathy and healthy controls (p = 0.03 and p = 0.008, respectively).

CONCLUSIONS

We suggest that the high plasma IL-18 levels observed in DADA2 patients with hematologic manifestations may be associated with an activated IFNγ pathway, and lack of response to anti-TNF treatment. We identified sRAGE as a potential biomarker of neuropathy in DADA2 patients. Higher concentrations of Tie-1, Tie-2, sFlt-1, sRAGE, and TNF-α distinguished DADA2 patients with PAN-like features from PAN patients.

Expanding spectrum of DADA2: a review of phenotypes, genetics, pathogenesis and treatment

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic disease caused by biallelic mutations in ADA2 gene (previously CECR1). The aim of this review was to describe the clinical phenotypes, genetics, pathogenesis and treatment of DADA2. ADA2 is highly expressed on myeloid cells and deficiency leads to polarisation of macrophages to an M1 inflammatory type and activation of neutrophils. The pathogenesis of immunological and haematological manifestations is less clear. The spectrum of clinical presentations varies widely from asymptomatic individual to severe vasculitis, several autoinflammatory, immunological and haematological manifestations. Initially considered a childhood disease, the first presentation is now being reported well into adulthood. Vasculitis closely resembles polyarteritis nodosa. Livedoid reticularis/racemosa like skin rash and central nervous system involvement in the form of ischemic or haemorrhagic stroke are dominant manifestations. Immunological manifestations include hypogammaglobulinemia and recurrent infections. Lymphopenia is the most common haematological manifestation; pure red cell aplasia and bone marrow failure has been reported in severe cases. The disease is extremely heterogeneous with variable severity noted in patients with the same mutation and even within family members. Tumour necrosis factor inhibitors are currently the treatment of choice for vasculitic and inflammatory manifestations and also prevent strokes. Haematopoietic stem cell transplantation is a curative option for severe haematological manifestations like pure red cell aplasia, bone marrow failure and immunodeficiency. Further research is required to understand pathogenesis and all clinical aspects of this disease to enable early diagnosis and prompt treatment. Key Points • Deficiency of adenosine deaminase 2 (DADA2) is a monogenic disease caused by biallelic mutations in ADA2 gene. • The clinical features include vasculitis resembling polyarteritis nodosa, autoinflammation, haematological manifestations and immunodeficiency. • The severity varies widely from mild to fatal even in patients within a family and with the same mutation. • The treatment of choice for inflammatory and vasculitic disease is tumour necrosis factor α blockers. Bone marrow transplant may be considered for severe haematological disease.

Impact of integrated translational research on clinical exome sequencing

PURPOSE

Exome sequencing often identifies pathogenic genetic variants in patients with undiagnosed diseases. Nevertheless, frequent findings of variants of uncertain significance necessitate additional efforts to establish causality before reaching a conclusive diagnosis. To provide comprehensive genomic testing to patients with undiagnosed disease, we established an Individualized Medicine Clinic, which offered clinical exome testing and included a Translational Omics Program (TOP) that provided variant curation, research activities, or research exome sequencing.

METHODS

From 2012 to 2018, 1101 unselected patients with undiagnosed diseases received exome testing. Outcomes were reviewed to assess impact of the TOP and patient characteristics on diagnostic rates through descriptive and multivariate analyses.

RESULTS

The overall diagnostic yield was 24.9% (274 of 1101 patients), with 174 (15.8% of 1101) diagnosed on the basis of clinical exome sequencing alone. Four hundred twenty-three patients with nondiagnostic or without access to clinical exome sequencing were evaluated by the TOP, with 100 (9% of 1101) patients receiving a diagnosis, accounting for 36.5% of the diagnostic yield. The identification of a genetic diagnosis was influenced by the age at time of testing and the disease phenotype of the patient.

CONCLUSION

Integration of translational research activities into clinical practice of a tertiary medical center can significantly increase the diagnostic yield of patients with undiagnosed disease.

Advances in cutaneous vasculitis research and clinical care

Vasculitis is characterized by inflammation and destruction of blood vessels, resulting in downstream ischemic tissue damage. Diagnosis of vasculitis is a careful exercise in clinical-pathologic correlation, depending upon the clinical manifestations, organs involved, the size of affected blood vessels, imaging, and laboratory findings. While some vasculitis subtypes may be confined to the skin, serious internal organ involvement or underlying disease states may also occur. Accordingly, the skin plays an important role in the diagnostic process and may be prognostically important in some cases, signifying more severe systemic disease. The skin also provides opportunities for tissue-based translational research, improving understanding of disease pathophysiology. Dermatologists, therefore, play a critical role in evaluating vasculitis and helping to advance vasculitis clinical care and research. Recent updates in vasculitis nomenclature and terminology, evidence-based diagnosis, pathogenesis, and investigations of targeted therapies are changing vasculitis research and leading to fundamental shifts in disease management. Treatment advances favoring evidence-based and targeted, rather than broadly immunosuppressive, therapies are in development, while a multicenter trial for skin-limited vasculitis is ongoing. Collaborative multidisciplinary research networks are key to current and future advances in vasculitis research. In this review, we describe recent developments in vasculitis clinical care and research, starting with a discussion of efforts to develop diagnostic and classification criteria, followed by updates on the evaluation and treatment of vasculitis.

Deficiency of Adenosine Deaminase 2 in Adults and Children: Experience From India

OBJECTIVE

Deficiency of adenosine deaminase 2 (DADA2) is a potentially fatal monogenic syndrome characterized by variable manifestations of systemic vasculitis, bone marrow failure, and immunodeficiency. Most cases are diagnosed by pediatric care providers, given the typical early age of disease onset. This study was undertaken to describe the clinical phenotypes and treatment response both in adults and in children with DADA2 in India.

METHODS

A retrospective analysis of pediatric and adult patients with DADA2 diagnosed at various rheumatology centers across India was conducted. Clinical characteristics, diagnostic findings, and treatment responses were analyzed in all subjects.

RESULTS

In total, 33 cases of DADA2 were confirmed in this cohort between April 2017 and March 2020. Unlike previous studies, nearly one-half of the confirmed cases presented during adulthood. All symptomatic patients exhibited features of vasculitis, whereas constitutional symptoms and anemia were more common in pediatric patients. Cutaneous and neurologic involvement were common, and 18 subjects had experienced at least one stroke. In addition, the clinical spectrum of DADA2 was expanded by recognition of novel features in these patients, including pancreatic infarction, focal myocarditis, and diffuse alveolar hemorrhage. Treatment with tumor necrosis factor inhibitors (TNFi) was initiated in 25 patients. All of the identified disease manifestations showed marked improvement after initiation of TNFi, and disease remission was achieved in 19 patients. Two cases were complicated by tuberculosis infection, and 2 deaths were reported.

CONCLUSION

This report presents the first case series of patients with DADA2 from India, diagnosed by adult and pediatric care providers. The findings raise awareness of this syndrome, particularly with regard to its presentation in adults.

Atypical pediatric presentation of lymphocytic thrombophilic arteritis: Diagnostic difficulties and recent nosological clarification

A 4-year-old girl presented with a 2-month history of round, hypopigmented, slightly scaly patches measuring 1-6 cm and encircled by an erythematous halo, first appearing on the lower limbs then spreading to the whole body. Three biopsies were taken as the condition progressed, each showing a lymphocytic infiltrate affecting a medium-sized artery at the dermal-subcutaneous junction, with a concentric fibrin ring. These findings are characteristic of lymphocytic thrombophilic arteritis (LTA). The young age of our patient and the type of skin lesions she developed make this an atypical presentation of LTA, which usually manifests as hyperpigmented macules on the lower extremities, predominantly in dark-skinned women.

Analysis of the Clinical Characteristics and Follow-up Study of Children with Cutaneous Polyarteritis Nodosa

OBJECTIVE

This study aims to analyze the clinical characteristics, treatment and prognosis of children with cutaneous polyarteritis nodosa (CPAN), in order to improve the understanding of this disease.

METHODS

Data of 14 children with CPAN, who were hospitalized in the Beijing Children's Hospital of Capital Medical University from January 2006 to December 2016, were collected. The clinical characteristics of all patients were summarized, the antistreptolysin-O (ASO)-positive and ASO-negative groups were compared, and the follow-up results were analyzed. X2-test, Fisher's exact probability test, t-test and Mann-Whitney test were used for statistical analysis.

RESULTS

Among these 14 CPAN patients, nodular rash was the most common manifestation (14/14). The ASO-positive group had more nodules in the lower limbs and the ASO-negative group appeared more in the upper limbs, which were statistically significant (p<0.05). ASOpositive children were more likely to have joint symptoms (P<0.05), and were more prone to elevated white blood cells (P<0.05). Follow-ups were performed on nine patients, and the prognoses were all good. The occurrence of systemic polyarteritis nodosa was not observed.

CONCLUSION

The main clinical manifestation of children with CPAN is skin nodules, which rarely affects the internal organs. Streptococcal infection is often the main cause. Anti-infection treatment should be simultaneously considered.

Update on vasculitis: overview and relevant dermatological aspects for the clinical and histopathological diagnosis - Part II

Vasculitis is a group of several clinical conditions in which the main histopathological finding is fibrinoid necrosis in the walls of blood vessels. This article assesses the main dermatological aspects relevant to the clinical and laboratory diagnosis of small- and medium-vessel cutaneous and systemic vasculitis syndromes. The most important aspects of treatment are also discussed.

Clusters in Pediatric Rheumatic Diseases

PURPOSE OF THE REVIEW

Rheumatic diseases usually have very diverse and complex pathophysiology resulting in different clinical phenotypes. Some certain phenotypes cluster together with a common presentation, course, and outcome. Our primary aim is to review the known disease clusters in certain rheumatological conditions.

RECENT FINDINGS

Cluster analysis has been reported in several rheumatic diseases, Behcet disease being the most common. Five individual clusters together with some clinical associations have been reported in Behcet patients. Certain antibody-phenotype associations and damage clusters have been reported in systemic lupus erythematosus (SLE) patients as well. Although there is no proper cluster analysis, two distinct phenotypes are evident in deficiency of ADA2 (DADA2): those with a polyarteritis nodosa-like vasculopathy and hematological involvement with pure red cell aplasia or bone marrow failure. The variants are claimed to be different regions of this gene for these 2 phenotypes. Lastly, there is a recent paper grouping ANCA-associated vasculitis according to disease phenotype and antibody associations. There are distinct clusters in certain rheumatic diseases which might help us to predict comorbidities, disease course, and treatment response.

ADA2 deficiency complicated by EBV-driven lymphoproliferative disease

A 29-year old male with recurrent respiratory and skin infections, anaemia and neutropaenia during childhood required immunoglobulin replacement for antibody deficiency from age 16. He remained relatively well until age 28 when he presented with a two-week history of fatigue, sore throat, fever and productive cough. He was found to have EBV viraemia and splenomegaly and a diagnosis of EBV-driven lymphoproliferative disease was made following bone marrow trephine. Family history was notable with three siblings: a healthy sister and two brothers with anaemia and neutropaenia; one who succumbed to septicaemia secondary to neutropaenic enterocolitis age 5 and another who developed intestinal vasculitis and antibody deficiency and had a successful haemopoetic stem cell transplant.

The proband's DNA underwent targeted sequencing of 279 genes associated with immunodeficiency (GRID panel). The best candidates were two ADA2 variants, p.Arg169Gln (R169Q) and p.Asn370Lys (N370K). Sanger sequencing and co-segregation of variants in the parents, unaffected sister and all three affected brothers was fully consistent with compound heterozygous inheritance. Subsequent whole genome sequencing of the proband identified no other potential causal variants. ADA2 activity was consistent with a diagnosis of ADA2 deficiency in affected family members.

This is the first description of EBV-driven lymphoproliferative disease in ADA2 deficiency. ADA2 deficiency may cause susceptibility to severe EBV-induced disease and we would recommend that EBV status and viral load is monitored in patients with this diagnosis and allogeneic SCT is considered at an early stage for patients whose ADA2 deficiency is associated with significant complications.

•

We report a patient with ADA2 deficiency and EBV-driven lymphoproliferative disease.

•

ADA2 deficiency may predispose to severe EBV-induced disease.

•

We would recommend that EBV status and viral load is monitored in patients with ADA2 deficiency.

Hypertensive Crisis: The Other Side of Polyarteritis Nodosa

Hypertensive crisis is a deadly complication that should be avoided at all costs, let alone when it is associated with a rare disease, such as polyarteritis nodosa. We present a case of a child who initially came to our hospital with a prolonged high-grade fever responding to antipyretics. Upon follow up, the patient went into a hypertensive crisis, which led to the admission to the Pediatric Intensive Care Unit (PICU). The hypertension was difficult to control until the culprit was revealed. Polyarteritis nodosa was then diagnosed by angiography, which revealed tight stenosis of the right renal artery. Prompt treatment was initiated, and the patient's blood pressure normalized. Our case highlights the importance of detecting such diseases, since it may be easily missed as it usually presents with nonspecific symptoms. Hypertension in children shouldn't be taken lightly and should be investigated promptly. We hope our case report sheds enough light on this issue for other clinicians and researches to identify and prevent later on.

Human adenosine deaminase 2 deficiency: A multi-faceted inborn error of immunity

Human adenosine deaminase 1 deficiency was described in the 1970s to cause severe combined immunodeficiency. The residual adenosine deaminase activity in these patients was attributed to adenosine deaminase 2. Human adenosine deaminase type 2 deficiency (DADA2), due to biallelic deleterious mutations in the ADA2 gene, is the first described monogenic type of small- and medium-size vessel vasculitis. The phenotype of DADA2 also includes lymphoproliferation, cytopenia, and variable degrees of immunodeficiency. The physiological role of ADA2 is still enigmatic hence the pathophysiology of the condition is unclear. Preliminary data showed that in the absence of ADA2, macrophage differentiation is skewed to a pro-inflammatory M1 subset, which is detrimental for endothelial integrity. The inflammatory phenotype responds well to anti-TNF therapy with etanercept and that is the first-line treatment for prevention of severe vascular events including strokes. The classic immunosuppressive drugs are not successful in controlling the disease activity. However, hematopoietic stem cell transplantation (HSCT) has been shown to be a definitive cure in DADA2 patients who present with a severe cytopenia. HSCT can also cure the vascular phenotype and is the treatment modality for patients' refractory to anti-cytokine therapies. In this review, we describe what is currently known about the molecular mechanisms of DADA2. Further research on the pathophysiology of this multifaceted condition is needed to fine-tune and steer future therapeutic strategies.

Cutaneous polyarteritis nodosa in pediatric patients successfully treated with TNF-α inhibitor and methotrexate: Case series and literature review

Cutaneous polyarteritis nodosa (CPAN) is a rare necrotizing vasculitis affecting small- to medium-sized arteries. Reported treatments include oral corticosteroids alone or in combination with non-steroidal antiinflammatory drugs, intravenous immunoglobulins, cyclophosphamide, azathioprine, colchicine, or dapsone. However, some patients with CPAN do not respond to such treatments and continue to experience exacerbations over prolonged periods. This series provides support for the use of TNF-α inhibitors in the treatment of recalcitrant CPAN in pediatric patients.

Dermatologic and Dermatopathologic Features of Monogenic Autoinflammatory Diseases

Autoinflammatory diseases include disorders with a monogenic cause and also complex conditions associated to polygenic or multifactorial factors. An increased number of both monogenic and polygenic autoinflammatory conditions have been identified during the last years. Although skin manifestations are often predominant in monogenic autoinflammatory diseases, clinical and histopathological information regarding their dermatological involvement is still scarce. Monogenic autoinflammatory diseases with cutaneous expression can be classified based on the predominant lesion: (1) maculopapular rashes or inflammatory plaques; (2) urticarial rashes; (3) pustular, pyogenic or neutrophilic dermatosis-like rashes; (4) panniculitis or subcutaneous nodules; (5) vasculitis or vasculopathy; (6) hyperkeratotic lesions; (7) hyperpigmented lesions; (8) bullous lesions; and (9) aphthous lesions. By using this classification, this review intends to provide clinical and histopathological knowledge about cutaneous involvement in monogenic autoinflammatory diseases.

[Update: polyarteritis nodosa]

Polyarteritis nodosa (PAN) is a necrotizing arteritis of medium-sized vessels, which is often fatal if untreated. It frequently affects the skin (nodules and ulcers), the peripheral nervous system (mononeuritis multiplex) and the visceral vessels (stenoses and microaneurysms). The complex diagnostic work-up requires discriminating PAN from infectious, malignant, drug-induced and other inflammatory conditions. It can be subclassified into further variants (idiopathic, associated with hepatitis B, associated with hereditary inflammatory diseases or isolated cutaneous disease). While idiopathic and hereditary inflammatory variants require immunosuppressive treatment, the hepatitis B-associated variant is treated with virustatic agents and plasmapheresis. The isolated cutaneous variant has a good prognosis and rarely requires highly potent immunosuppressives.

Clinical Applications and Utility of a Precision Medicine Approach for Patients With Unexplained Cytopenias

OBJECTIVE

To demonstrate experience and feasibility of a precision medicine approach for patients with unexplained cytopenias, defined as low blood counts in one or more cell lineages, persistent for 6 months or longer, in the absence of known nutritional, autoimmune, infectious, toxic, and neoplastic (secondary) causes.

PATIENTS AND METHODS

Patients were evaluated in our clinic between November 8, 2016, and January 12, 2018. After a thorough evaluation of known causes, family history, and appropriate clinical assays, genomic evaluation was performed in a stepwise manner, through Sanger, targeted, and/or whole-exome sequencing. Variants were analyzed and discussed in a genomics tumor board attended by clinicians, bioinformaticians, and molecular biologists.

RESULTS

Sixty-eight patients were evaluated in our clinic. After genomic interrogation, they were classified into inherited bone marrow failure syndromes (IBMFS) (n=24, 35%), cytopenias without a known clinical syndrome which included idiopathic and clonal cytopenias of undetermined significance (CCUS) (n=30, 44%), and patients who did not fit into the above two categories ("others," n=14, 21%). A significant family history was found in only 17 (25%) patients (9 IBMFS, 2 CCUS, and 6 others), whereas gene variants were found in 43 (63%) patients (34 [79%] pathogenic including 12 IBMFS, 17 CCUS, and 5 others]. Genomic assessment resulted in a change in clinical management in 17 (25%) patients, as evidenced by changes in decisions with regards to therapeutic interventions (n=8, 47%), donor choice (n=6, 35%), and/or choice of conditioning regimen for hematopoietic stem cell transplantation (n=8, 47%).

CONCLUSION

We show clinical utility of a real-world algorithmic precision medicine approach for unexplained cytopenias.

Cutaneous Polyarteritis Nodosa Treated with Pentoxifylline and Clobetasol Propionate: A Case Report

Cutaneous polyarteritis nodosa is a rare type of cutaneous vasculitis. It affects the small- and medium-sized arteries of the dermis and subcutaneous tissue without extracutaneous involvement. The diagnosis is by skin biopsy, and the characteristic finding is a leukocytoclastic vasculitis. We report a case of a 14-year-old Saudi girl who was referred to the dermatology service because of multiple ulceronecrotic lesions on the frontal aspects of the distal lower limbs. She had past medical consultations and treatment but without improvement. The histopathology confirmed the clinical diagnosis of cPAN, and ultimately, she responded to treatment with pentoxifylline and topical clobetasol propionate. It is important to be aware of this disease and refer the patient to the dermatology service for the appropriate evaluation and treatment.

Biochemistry of Autoinflammatory Diseases: Catalyzing Monogenic Disease

Monogenic autoinflammatory disorders are a group of conditions defined by systemic or localized inflammation without identifiable causes, such as infection. In contrast to classical primary immunodeficiencies that manifest with impaired immune responses, these disorders are due to defects in genes that regulate innate immunity leading to constitutive activation of pro-inflammatory signaling. Through studying patients with rare autoinflammatory conditions, novel mechanisms of inflammation have been identified that bare on our understanding not only of basic signaling in inflammatory cells, but also of the pathogenesis of more common inflammatory diseases and have guided treatment modalities. Autoinflammation has further been implicated as an important component of cardiovascular, neurodegenerative, and metabolic syndromes. In this review, we will focus on a subset of inherited enzymatic deficiencies that lead to constitutive inflammation, and how these rare diseases have provided insights into diverse areas of cell biology not restricted to immune cells. In this way, Mendelian disorders of the innate immune system, and in particular loss of catalytic activity of enzymes in distinct pathways, have expanded our understanding of the interplay between many seemingly disparate cellular processes. We also explore the overlap between autoinflammation, autoimmunity, and immunodeficiency, which has been increasingly recognized in patients with dysregulated immune responses.

Renal Amyloidosis in Deficiency of Adenosine Deaminase 2: Successful Experience With Canakinumab

Deficiency of adenosine deaminase 2 (DADA2) is a rare autoinflammatory disease that was firstly described in patients with early-onset strokes, livedo reticularis, and periodic fever resembling polyarteritis nodosa. In reported case series, researchers described highly variable manifestations, including autoimmunity, immunodeficiency, hepatosplenomegaly, pancytopenia, ichthyosiform rash, and arthritis, in patients with DADA2. A thirteen-year-old female patient who was born to consanguineous parents was admitted to our hospital with generalized edema and leg pain. A physical examination revealed splenomegaly and left knee arthritis. Nephrotic-range proteinuria and hypoalbuminemia were present, and a renal biopsy revealed amyloidosis. Despite the absence of periodic fever and livedo reticularis, our patient had suggestive features of DADA2, including low serum immunoglobulin G and immunoglobulin M levels, hepatosplenomegaly, and renal amyloidosis. We found a heterozygote Met694Val mutation in the Mediterranean fever gene and a novel homozygote Thr317Argfs*25 (c.950-950delCys) mutation in the cat eye chromosome region 1 gene. A functional analysis revealed absent plasma adenosine deaminase 2 activity. Canakinumab was administered because of unresponsive proteinuria despite 2 months of treatment with colchicine and methylprednisolone. Proteinuria improved after 7 doses of canakinumab. In conclusion, DADA2 should be considered in the differential diagnosis of renal amyloidosis, particularly in the absence of homozygote Mediterranean fever mutations. Although anti-tumor necrosis factor agents are widely offered in DADA2 treatment, we speculate that canakinumab may be an appropriate treatment of renal amyloidosis in DADA2.

ADA2 Deficiency Mimicking Idiopathic Multicentric Castleman Disease

Multicentric Castleman disease (MCD) is a rare entity that, unlike unicentric Castleman disease, involves generalized polyclonal lymphoproliferation, systemic inflammation, and multiple-organ system failure resulting from proinflammatory hypercytokinemia, including, in particular, interleukin-6. A subset of MCD is caused by human herpesvirus-8 (HHV-8), although the etiology for HHV-8-negative, idiopathic MCD (iMCD) cases is unknown at present. Recently, a consensus was reached on the diagnostic criteria for iMCD to aid in diagnosis, recognize mimics, and initiate prompt treatment. Pediatric iMCD remains particularly rare, and differentiation from MCD mimics in children presenting with systemic inflammation and lymphoproliferation is a challenge. We report on a young boy who presented with a HHV-8-negative, iMCD-like phenotype and was found to suffer from the monogenic disorder deficiency of adenosine deaminase 2 (DADA2), which is caused by loss-of-function mutations in CECR1 DADA2 prototypic features include early-onset ischemic and hemorrhagic strokes, livedoid rash, systemic inflammation, and polyarteritis nodosa vasculopathy, but marked clinical heterogeneity has been observed. Our patient's presentation remains unique, with predominant systemic inflammation, lymphoproliferation, and polyclonal hypergammaglobulinemia but without apparent immunodeficiency. On the basis of the iMCD-like phenotype with elevated interleukin-6 expression, treatment with tocilizumab was initiated, resulting in immediate normalization of clinical and biochemical parameters. In conclusion, iMCD and DADA2 should be considered in the differential diagnosis of children presenting with systemic inflammation and lymphoproliferation. We describe the first case of DADA2 that mimics the clinicopathologic features of iMCD, and our report extends the clinical spectrum of DADA2 to include predominant immune activation and lymphoproliferation.

Deficiency of Adenosine Deaminase 2 (DADA2): Updates on the Phenotype, Genetics, Pathogenesis, and Treatment

Deficiency of ADA2 (DADA2) is the first molecularly described monogenic vasculitis syndrome. DADA2 is caused by biallelic hypomorphic mutations in the ADA2 gene that encodes the adenosine deaminase 2 (ADA2) protein. Over 60 disease-associated mutations have been identified in all domains of ADA2 affecting the catalytic activity, protein dimerization, and secretion. Vasculopathy ranging from livedo reticularis to polyarteritis nodosa (PAN) and life-threatening ischemic and/or hemorrhagic stroke dominate the clinical features of DADA2. Vasculitis and inflammation can affect many organs, explaining the intestinal, hepatological, and renal manifestations. DADA2 should be primarily considered in patients with early-onset fevers, rashes, and strokes even in the absence of positive family history. Hematological manifestations include most commonly hypogammaglobulinemia, although pure red cell aplasia (PRCA), immune thrombocytopenia, and neutropenia have been increasingly reported. Thus, DADA2 may unify a variety of syndromes previously not thought to be related. The first-line treatment consists of TNF-inhibitors and is effective in controlling inflammation and in preserving vascular integrity. Hematopoietic stem cell transplantation (HSCT) has been successful in a group of patients presenting with hematological manifestations. ADA2 is highly expressed in myeloid cells and plays a role in the differentiation of macrophages; however, its function is still largely undetermined. Deficiency of ADA2 has been linked to an imbalance in differentiation of monocytes towards proinflammatory M1 macrophages. Future research on the function of ADA2 and on the pathophysiology of DADA2 will improve our understanding of the condition and promote early diagnosis and targeted treatment.

A decision tree for the genetic diagnosis of deficiency of adenosine deaminase 2 (DADA2): a French reference centres experience

Deficiency of adenosine deaminase 2 (DADA2) is a recently described autoinflammatory disorder. Genetic analysis is required to confirm the diagnosis. We aimed to describe the identifying symptoms and genotypes of patients referred to our reference centres and to improve the indications for genetic testing. DNA from 66 patients with clinically suspected DADA2 were sequenced by Sanger or next-generation sequencing. Detailed epidemiological, clinical and biological features were collected by use of a questionnaire and were compared between patients with and without genetic confirmation of DADA2. We identified 13 patients (19.6%) carrying recessively inherited mutations in ADA2 that were predicted to be deleterious. Eight patients were compound heterozygous for mutations. Seven mutations were novel (4 missense variants, 2 predicted to affect mRNA splicing and 1 frameshift). The mean age of the 13 patients with genetic confirmation was 12.7 years at disease onset and 20.8 years at diagnosis. Phenotypic manifestations included fever (85%), vasculitis (85%) and neurological disorders (54%). Features best associated with a confirmatory genotype included fever with neurologic or cutaneous attacks (odds ratio [OR] 10.71, p = 0.003 and OR 10.9, p < 0.001), fever alone (OR 8.1, p = 0.01), and elevated C-reactive protein (CRP) level with neurologic involvement (OR 6.63, p = 0.017). Our proposed decision tree may help improve obtaining genetic confirmation of DADA2 in the context of autoinflammatory symptoms. Prerequisites for quick and low-cost Sanger analysis include one typical cutaneous or neurological sign, one marker of inflammation (fever or elevated CRP level), and recurrent or chronic attacks in adults.

Diagnosis and management of ADA2 deficient polyarteritis nodosa

Deficiency of ADA2 (DADA2) is a recently described systemic inflammatory vasculopathy caused by mutations in the CERC1 gene that often, but not always, clinically resembles polyarteritis nodosa (PAN). The condition was originally characterized by livedoid rash, systemic inflammation, variable hypogammaglobulinemia, and early-onset stroke. The phenotypic spectrum has expanded to include patients with immunodeficiency syndromes and bone marrow dysfunction, which are not typical features of PAN. Exploration into the pathogenesis and treatment options of DADA2 has added to our understanding of this condition, but more studies are needed. The purpose of this article is to review the various clinical phenotypes of DADA2, and raise awareness among rheumatologists to consider DADA2 when evaluating patients presenting with PAN-like disease.

Vasculopathy, Immunodeficiency, and Bone Marrow Failure: The Intriguing Syndrome Caused by Deficiency of Adenosine Deaminase 2

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic form of systemic vasculopathy that often presents during early childhood. Linked to biallelic mutations in ADA2 (previously CECR1), DADA2 was initially described as a syndrome of recurrent fever, livedo racemosa, early-onset strokes, and peripheral vasculopathy that resembles polyarteritis nodosum. However, the wide spectrum of clinical findings and heterogeneity of disease, even among family members with identical mutations, is increasingly recognized. Evidence of systemic inflammation and vasculopathy is not uniformly present in DADA2 patients and some can remain asymptomatic through adulthood. Humoral immunodeficiency characterized by low immunoglobulin levels and increased risk of infection is another common feature of DADA2. Variable cytopenias including pure red cell aplasia that mimics Diamond-Blackfan anemia can also be primary manifestations of DADA2. How defects in a single gene translate into these heterogeneous presentations remains to be answered. In this review, we will summarize lessons learned from the pleiotropic clinical manifestations of DADA2.

[Multiple facets of ADA2 deficiency: Vasculitis, auto-inflammatory disease and immunodeficiency: A literature review of 135 cases from literature]

Deficiency of adenosine deaminase 2 (DADA2) is a recently described auto-inflammatory disorder. It is an autosomal recessive inherited disease, caused by mutations in the ADA2 gene (formerly known as CECR1) encoding ADA2 enzyme. Besides its role in the purine metabolism, it has been postulated that ADA2 may act as a growth factor for endothelial cells and in the differenciation of monocytes. Thus, deficiency of ADA2 would lead to endothelial damage and a skewing of monocytes into M1 pro-inflammatory macrophage, causing DADA2 manifestations. Three core clinical features have been described: inflammatory-vascular signs, hematologic abnormalities and immunodeficiency. Clinically, patients display intermittent fever, cutaneous vascular manifestations, such as livedo, ischemic strokes, arthralgia and abdominal pain crisis. Corticosteroids and immunosuppressive agents (i.e. cyclophosphamide, azathioprine, ciclosporin, methotrexate) appear to be poorly effective. Although the mechanism has not been elucidated, anti-TNF agents have been proven efficient in DADA2 and should therefore be used as first line therapy for vasculitis. Role of anti-platelet and anticoagulant therapies in stroke-prophylaxis remains to be discussed, as those patients display a high risk of intracranial bleeding.

Vasculitis and vasculitis-like manifestations in monogenic autoinflammatory syndromes

Monogenic autoinflammatory syndromes are a rare group of disorders characterized by periodic episodes of systemic inflammation of endogenous origin. Sometimes, these diseases may present with features akin to vasculitis. We conducted a literature review on such vasculitic manifestations in described monogenic autoinflammatory syndromes utilizing the Online Mendelian Inheritance in Man (OMIM), Medline, and Scopus databases. Our search identified that Familial Mediterranean fever (FMF) can manifest with features of either small, medium, large, or variable-vessel vasculitis. Stimulator of interferon gene (STING)-associated vasculopathy of infancy (SAVI) is an interferonopathy that can mimic the presentation of medium-vessel or small-vessel vasculitis, whereas deficiency of adenosine deaminase 2 (DADA2) is another such mimic of medium-vessel vasculitis, associated in a significant number of patients with features of immunodeficiency. Occasional reports exist of vasculitic manifestations in tumor necrosis factor (TNF) receptor-associated periodic fever syndrome (TRAPS) and chronic infantile neurologic cutaneous and articular disorder (CINCA), whereas mevalonate kinase deficiency can also mimic the presentation of small- or medium-vessel vasculitis. Clinicians should be aware of the possibility of autoinflammatory disease presenting as vasculitis to diagnose and treat the same appropriately.

Refractory Pure Red Cell Aplasia Manifesting as Deficiency of Adenosine Deaminase 2

Primary progress has been made in the last 2 years, particularly in finding novel disease-causing genes for a number of autoinflammatory diseases and primary immunodeficiencies. Whole-exome sequencing has dramatically increased the pace at which causative genes are being discovered. CECR1 (Cat eye syndrome chromosome region, candidate 1) gene encodes adenosine deaminase 2 (ADA2) protein. Patients who carry CECR1 mutation(s) suffer from deficiency of ADA2 (DADA2). Here, we describe a patient with pure red cell aplasia discovered to have DADA2. We also review the literature on DADA2. This report will help raise awareness of physicians for this complex disease.

No shortcuts: new findings reinforce why nuance is the rule in genetic autoinflammatory syndromes

PURPOSE OF REVIEW

Practitioners dazed by the evolving concept of autoinflammation are in good company. Despite the clinical challenges autoinflammatory patients present, their study has been fundamental to our understanding of basic human inflammation. This review will focus on the ways in which recent discoveries in genetically mediated autoinflammation broaden and refine the concept.

RECENT FINDINGS

Major developments in pyrin inflammasome biology, defective ubiquitination, and the hyperferritinemic syndromes will be highlighted.

SUMMARY

We offer a brief discussion of discordance, convergence, genotype, and phenotype in autoinflammation. Additionally, we introduce the concepts of mutation dose effect and hybrid nomenclature. Overall, we hope to provide an update on developments in the field of autoinflammation, some conceptual tools to help navigate the rising tide of discovery, and some encouragement that keeping up with developments in autoinflammation is both exciting and necessary.