ADA2 Deficiency Research Articles

Peduncular Hallucinosis: Clinical characteristics, etiology, and a case report

IntroductionVisual hallucinations are a relatively common neurological complaint. Peduncular hallucinosis (PH) stands out as a distinct entity, characterized by complex visual hallucinations resulting from structural lesions in the brainstem or diencephalon.ObjectivesWe aim to provide an overview of the clinical features, etiological factors, and management strategies associated with PH, incorporating a unique case study.MethodsClinical case report and brief literature review.ResultsClinical Characteristics: PH is marked by detailed, colorful, vivid, and occasionally emotionally charged visual hallucinations. These hallucinations encompass people, animals, or objects and may be mistaken for reality. While primarily visual, they may occasionally involve other sensory modalities. Crucially, patients with PH maintain insight, distinguishing it from primary psychotic disorders.Etiological Factors: PH is most commonly associated with structural brainstem lesions, particularly in the midbrain. Potential instigators encompass ischemic strokes, vascular anomalies, tumors and infections. Disruption of the reticular activating system in the brainstem is implicated in the pathogenesis. Advanced imaging techniques have unveiled cases with subtle presentations, broadening our comprehension of PH.Pathogenesis: PH may involve the disturbance of serotonergic inhibitory pathways and the reticular activating system. A plausible link with hypnagogic hallucinations hints at a mechanism related to rapid REM sleep transitions.Case Report: Mr. J., a 30-year-old patient, suffered recurrent mesencephalic strokes attributed to Sneddon’s syndrome, ADA-2 deficiency, and protein C deficiency, leading to malacic lesions in the hemimesencephalon and right hemipons. He experienced complex visual hallucinations, primarily geometric patterns and animals, mainly at night. Importantly, he maintained insight into their hallucinatory nature. Mr. J. also had diplopia, visual impairment, recurrent headaches, and left hemiparesis.Reactive anxiety and depression due to functional loss followed his recurrent strokes. Initially, antipsychotics were used to manage sensory-perceptual disturbances, but were later discontinued due to reduced interference with daily functioning. Antidepressant and psychological therapy was continued throughout the follow-up to address mood symptoms.Conclusions Peduncular hallucinosis is an intriguing phenomenon characterized by complex visual hallucinations. Understanding its clinical features, etiology, and possible mechanisms is essential for accurate diagnosis and management. This case report emphasizes PH’s clinical aspects and the importance of a multidisciplinary approach, including pharmacological intervention and psychological support. Understanding its features, causes, and management is essential for accurate care. Further research is needed to improve our comprehension and optimize treatment strategies.Disclosure of InterestNone Declared

A Single-Center Large Cohort of Chronic Neutropenia Patients and a Model for Estimation of Congenital Neutropenias

Chronic neutropenia (CrN) is defined as neutropenia lasting longer than 3 months and has various underlying etiologies, including congenital neutropenia (CN). We aimed to determine the underlying etiologies of patients with CrN and define the characteristics at diagnosis suggestive for CN as a final diagnosis. The study included 197 pediatric and adolescent patients who were diagnosed with CrN between 2010 and 2022 in a single-center. Patients with transient neutropenia, splenomegaly, alloimmune, secondary autoimmune, myelodysplastic syndrome and hematological malignancies, other bone marrow failure syndromes such as Fanconi anemia, and aplastic anemia due to CrN were excluded from the study. The patients included in the study were sub-classified into 5 groups according to their final diagnosis. Group 1, patients with CN (n=64, %32.5) included all genetically verified CrN patients. Group 2, patients with primary autoimmune neutropenia (pIN) group (n=10, %5.1) with anti-granulocyte antibody (AGA) positivity. Group 3, patients with unclassified chronic idiopathic neutropenia (UCIN) (n=73, %37.1). Group 3 included patients who had a clinical severity resembling immune neutropenia, but whose AGA testing was either negative or not available; but the CrN resolved during follow-up. Group 4, included the patients with unclassified chronic benign neutropenia (UCBN) (n=34, %17.3) and included the patients with ongoing neutropenia, who do not have a history of serious infections, no underlying genetic cause for neutropenia, no AGA positivity. Group 5, unspecified congenital neutropenia (UCN) group (n=16, %8,1), was defined as the group of patients whose genetic tests did not detect a mutation in genes related to CN, but history reveales severe infections and a possible CN as an underlying cause. Genetic testing of patients varies from single gene evaluation with Sanger sequencing analysis to Whole Exome Sequencing (WES). The median age at diagnosis of neutropenia of the patients included in the study was 12 (0-168) months 53.8% of the patients were male (n=106). There was consanguinity between parents in 34.5% and at least 1 family member was diagnosed with neutropenia in the in 18.8%. Among the patients in Group 1, HAX-1 mutation was detected in 19 (29.7%) patients and it was found to be the most common genetic defect causing CN. Other common genetic disorders include ELANE mutations (18.8%), Shwachman Diamond Syndrome (10.9%), Hermansky Pudlak Syndrome (7.8%) and glycogen storage type 1 b (6.3%). G6PC3 deficiency, VPS45 deficiency, Barth syndrome and Kabuki syndrome in 2 each (3.1%), ADA2 deficiency, Cohen Syndrome, Poikiloderma with neutropenia, Prolidase deficiency, CLPB deficiency, Majeed syndrome, GINS4 deficiency, reticular dysgenesis, germline RUNX1 mutation were detected in 1 patient. There are 3 patients with acute myeloid leukemia and all of them died before hematopoietic stem cell transplantation (HSCT). Two of these patients were diagnosed with SDS, and one had ELANE mutation. One patient with the HAX-1 mutation developed non-Hodgkin lymphoma and was treated with HSCT and is still alive. There were 7 patients (3.6%) who underwent HSCT. 9 patients (4.6%) died. Except for 3 patients who died from AML and 1 who died after HSCT; 1 patient with Barth syndrome deceased related to associated dilated cardiomyopathy, Another patient with G6PC3 mutation died after complications of cardiac surgery due to associated cardiac anomaly and 3 patients (2 VPS45, 1 CLPB) died due to infections. Patients in Group1 and Group 2+Group3 were compared, in order to answer the question of “Can we create a model that predicts CN?”. Many parameters were compared and a multivariate model was created with statistically significant risk factors. CN was seen 6,3 times more in those with parental consanguinity, 8,9 times in those with a family history of neutropenia, 4,8 times in those with more than 2 hospitalizations due to infection, and 4,1 times more in those with recurrent oral involvement (p<0.05). Patients diagnosed with CN were estimated based on the results of the multifactor logistic regression model. The rate of correct identification of the patients by the model is 88.9%. In conclusion, our study is one of the largest single-center studies and suggests a novel classification of CrN patients.

P19 Our experience diagnosing and treating deficiency of adenine deaminase 2 (DADA2) vasculitis

Abstract Introduction Deficiency of adenine deaminase 2 (DADA2) is caused by biallelic pathogenic variants in the gene on chromosome 22q11. It is autosomal recessive with incomplete penetrance, and a variable presentation. It typically manifests as a systemic vasculopathy with early onset strokes, cutaneous manifestations, immunodeficiency and cytopenia. Traditional immunosuppressants have limited efficacy, but vasculitic manifestations have been reported to respond to biologic TNF-inhibitors. We report a patient with confirmed ADA2 deficiency whose cutaneous manifestations were previously classified as Sneddon syndrome. After a period of stability on adalimumab she developed marked cutaneous ulceration that healed following a therapy switch to intravenous infliximab. Case description We report a 39-year-old female with a long clinical history that started in childhood when she developed Diamond-Blackfan anaemia that went into remission following corticosteroid treatment and transfusions. In 2006, she suddenly had two thalamic infarcts and was thoroughly investigated but was found to have unremarkable vascular imaging, a negative antiphospholipid syndrome and autoantibody testing, a modestly elevated CRP (5-15 mg/L) and a notably persistent low serum IgM. She continued to experience frequent migraines associated with transient sensorimotor symptoms. Subsequently, she developed recurrent botchy, polymorphic macular eruptions on the lower limbs. A deep cutaneous biopsy demonstrated lymphocytic predominant perivascular inflammation of deep dermal vessels associated with thrombus formation and endothelial proliferation. A putative diagnosis of Sneddon’s syndrome was made. However, after the subsequent identification of ADA2-deficiency vasculitis, the patient underwent genetic screening which identified a compound heterozygosity for two novel ADA2 mutations (c6634_636, delTTC (p.Phe212del) and c.1225C>T (p.Pro409Ser)). Her mother was as a carrier. She was started on adalimumab injections to which she had a good clinical response with improved cutaneous disease and no further neurological symptoms. However, after two years of disease stability, she then developed a significant ‘punched out’ ulcer on the mid-calf which was painful and increasing in size to a maximum of 2 x 3 cm. Dermatology colleagues were reluctant to re-biopsy due to a high likelihood of non-specific appearances and increased risk of poor healing leading to worsening ulceration. Drawing on experience from rheumatoid arthritis that a switch in anti-TNF biological will often restore efficacy following secondary non-response to adalimumab; we empirically switched treatment to intravenous infliximab, with a reducing course of prednisolone (40mg per day tapering to 5mg after 12 weeks). This was associated with a notable improvement within one month and a complete healing of the ulcer within 4 months. Discussion DADA2 remains a rare condition with a carrier frequency estimated at 1 in 236 persons worldwide and a predicted disease prevalence of approximately 1 in 222,000 persons. Patients with DADA2 who have haematological manifestations tend to present during early infancy, whereas delayed presentation is common in patients with vasculitis and systemic inflammation. It should be suspected in patients with early onset strokes, livedo and other haematological and immunological features. Additionally, many previously diagnosed cases of Sneddon syndrome may in fact have DADA2, with a low IgM level favouring the later. Diagnosis can be confirmed by genetic studies or by a biochemical assay that demonstrates near-absent levels of ADA2 activity in the plasma or serum. Interestingly, on screening of adult patients with polyarteritis nodosa (PAN) 3.4% possessed biallelic pathogenic ADA2 variants and similarly, in genomic survey of patients with Diamond-Blackfan anaemia 2% possessed biallelic pathogenic ADA2 variants in the absence of the ribosomal protein gene mutations associated with it. Treatment is phenotype based with a preference for lifelong TNF inhibitor and biosimilar use in those with vasculitis and/or systemic inflammation, though not currently commissioned for this indication. Glucocorticoids, disease-modifying antirheumatic drugs, and other biologic agents may partially ameliorate systemic inflammation. Unfortunately, they are all ineffective for severe hematologic manifestations and hematopoietic cell transplantation (HCT) is currently the only treatment option. Treating asymptomatic patients and mildly symptomatic patients picked up on screening remains senior clinician led on a risk benefit basis. Disease activity is clinically monitored with an overall mortality rate estimated at 8%. Key learning points The main learning points for me included an increased awareness of this syndrome, its variable presentation, association with other autoimmune illnesses, diagnosis, and treatment initiation. In addition, I learnt about screening of family members, weighing the benefits versus risks when considering treating mildly symptomatic and asymptomatic patients, clinical monitoring for response, and when to switch to other anti-TNFs and biosimilars. From this conference, I would like to explore the experience of our rheumatology colleagues with similar cases.

Different Phenotypes of a New Mutation: Two Siblings with ADA-2 Deficiency Presenting with Anemia and Neutropenia (Case Reports and Literature Review)

Different Phenotypes of a New Mutation: Two Siblings with ADA-2 Deficiency Presenting with Anemia and Neutropenia (Case Reports and Literature Review)

Atypical childhood Takayasu arteritis – A case report

Childhood Takayasu arteritis is one of the most common vasculitis in paediatric age group. It predominantly involves the greater vessels such as aorta and its branches, leading to granulomatous inflammation. The process of inflammation gives rise to the symptoms based on thrombotic or aneurysmal phenomena. This is a case report of a 11-year-old girl diagnosed in an urban tertiary care centre in India with childhood Takayasu arteritis. The said child had first presented with non-specific symptoms such as leg ache, back ache and fever. Over the course of illness, the child developed hypertension and had also suffered from PRES (posterior reversible encephalopathy syndrome). Clinical examination was consistent with Takayasu arteritis, however with predominant medium-sized vessel involvement on imaging. Since this is a relatively atypical presentation, it was mandatory to rule out other causes of medium-vessel arteritis, especially DADA2 (deficiency of ADA2).

A brazilian nationwide multicenter study on deficiency of deaminase-2 (DADA2)

IntroductionThe deficiency of ADA2 (DADA2) is a rare autoinflammatory disease provoked by mutations in the ADA2 gene inherited in a recessive fashion. Up to this moment there is no consensus for the treatment of DADA2 and anti-TNF is the therapy of choice for chronic management whereas bone marrow transplantation is considered for refractory or severe phenotypes. Data from Brazil is scarce and this multicentric study reports 18 patients with DADA2 from Brazil.Patients and methodsThis is a multicentric study proposed by the Center for Rare and Immunological Disorders of the Hospital 9 de Julho - DASA, São Paulo - Brazil. Patients of any age with a confirmed diagnosis of DADA2 were eligible for this project and data on clinical, laboratory, genetics and treatment were collected.ResultsEighteen patients from 10 different centers are reported here. All patients had disease onset at the pediatric age (median of 5 years) and most of them from the state of São Paulo. Vasculopathy with recurrent stroke was the most common phenotype but atypical phenotypes compatible with ALPS-like and Common Variable Immunodeficiency (CVID) was also found. All patients carried pathogenic mutations in the ADA2 gene. Acute management of vasculitis was not satisfactory with steroids in many patients and all those who used anti-TNF had favorable responses.ConclusionThe low number of patients diagnosed with DADA2 in Brazil reinforces the need for disease awareness for this condition. Moreover, the absence of guidelines for diagnosis and management is also necessary (t).

Molecular profile of patients with inborn errors of immunity from Nepal

Background and AimsInborn errors of immunity (IEIs) are increasingly being diagnosed in various regions of the world. There are significant challenges in the diagnosis and treatment of IEIs in resource-limited countries. With the availability of one immunologist and increasing awareness, IEIs are diagnosed with increasing frequency and accuracy in Nepal. IEIs are also being evaluated in children presenting with autoimmune manifestations. We describe the profile of patients diagnosed with IEIs in Nepal during 2020–2022. MethodsRecords of all patients with IEIs who were diagnosed and treated at our tertiary care center in Nepal from August 2020 to April 2022 were analysed. Lead author (DB) has examined and diagnosed all cases. IEIs were diagnosed based on the European Society for Immunodeficiencies (ESID) diagnostic criteria and genetic analysis. ResultsThirty-two patients with IEI (19 boys; 13 girls) and 801 children with autoimmune disorders were diagnosed during the study period. Genetic analysis was done on 18 patients. The diagnostic profile of the patients includes patients with chronic granulomatous disease, X-linked agammaglobulinemia, severe combined immunodeficiency, Job syndrome, selective IgA deficiency, specific antibody deficiency, Wiskott-Aldrich Syndrome, CTLA4 deficiency, IPEX syndrome, IFN-IL12 axis defect, hereditary angioedema, MonoMac syndrome, ARPC1B deficiency, leukocyte adhesion defect, PAPA syndrome, autoimmune lymphoproliferative syndrome, ADA2 deficiency, early-complement deficiency lupus, familial cold auto-inflammatory syndrome, A20 haploinsufficiency, and Blau syndrome. Some patients succumbed before the scope of diagnosis. HSCT is planned for 3 patients. ConclusionsOur is the first report of genetically proven IEIs in Nepal. Logistic constraints coupled with a lack of awareness of IEIs among laity and pediatrician accounted for a missed diagnosis, late diagnosis, and poor outcomes in resource-limited settings. Antimicrobial prophylaxis reduced the incidence of breakthrough infections. The lack of HSCT facilities precludes definitive treatment of many IEIs.

Break down the barriers of auto-inflammation: How to deal with a monogenic auto-inflammatory disease and immuno-haematological features in 2022?

In the past few years, the spectrum of monogenic systemic auto-inflammatory diseases (MSAID) has widely expanded beyond the typical recurrent fever. Immuno-haematological features, as cytopenias, hypogammaglobulinemia, hypereosinophilia, lymphoproliferation and immunodeficiency, have been described in association of several MSAID. The objective of this review was to describe these particular MSAID. MSAID must be suspected in front of immuno-haematological features associated with non-infectious recurrent fever, chronic systemic inflammation, inflammatory cutaneous manifestations, arthritis or inflammatory bowel disease. Genes and cellular mechanisms involved are various but some of them are of special interest. Defects in actine regulation pathway are notably associated with cytopenia and immune deficiency. Because of their frequency, ADA2 deficiency and Vacuoles, E1-Enzyme, X-linked, auto-inflammatory, Somatic (VEXAS) syndrome deserve to be noticed. ADA2 deficiency results in polyarteritis nodosa-like presentation with a wide panel of manifestations including cytopenia(s), lymphoproliferation and immune deficiency. Neutrophilic dermatosis or chondritis associated with macrocytic anaemia or myelodysplasia should lead to screen for VEXAS. Of note, most of MSAID are associated with inflammatory anaemia. We proposed here a clinical and pragmatic approach of MSAID associated with immuno-haematological features.

Pathogenic variant c.1052T>A (p.Leu351Gln) in adenosine deaminase 2 impairs secretion and elevates type I IFN responsive gene expression

BackgroundAdenosine deaminase 2 (ADA2) is a homodimeric, extracellular enzyme and putative growth factor that is produced by cells of the myeloid lineage and, catalytically, deaminates extracellular adenosine to inosine. Loss-of-(catalytic)-function variants in the ADA2 gene are associated with Deficiency of ADA2 (DADA2), an autosomal recessive disease associated with an unusually broad range of inflammatory manifestations including vasculitis, hematological defects and cytopenia. Previous work by our group led to the identification of ADA2 variants of novel association with DADA2, among which was a unique c.1052T>A (p.Leu351Gln; herein referred to as L351Q) variant located in the catalytic domain of the protein.MethodsMammalian (Flp-IN CHO) cells were engineered to stably express wild-type ADA2 and ADA2 protein variants, including the pathogenic L351Q variant identified in DADA2 patients. An enzyme assay and immunoblotting were used to assess ADA2 catalytic activity and secretion, respectively, and the outcome of experimentally induced inhibition of protein processing (Golgi transport and N-linked glycosylation) was assessed. Reverse transcription quantitative real-time PCR (RT-qPCR) was applied to determine the relative expression of Type I Interferon stimulated genes (ISGs), IFIT3 and IRF7.ResultsIn addition to abrogating catalytic activity, the L351Q variant impaired secretion of L351Q ADA2 resulting in an intracellular accumulation of L351Q ADA2 protein that was not observed in cells expressing wild-type ADA2 or other ADA2 protein variants. Retention of L351Q ADA2 was not attributable to impaired glycosylation on neighboring asparagine residues and did not impact cell growth or integrity. Constitutive expression of Type I ISGs IFIT3 and IRF7 was observed in cells expressing L351Q ADA2.ConclusionsThe impaired secretion of L351Q ADA2 may be an important factor leading to the severe phenotype observed in patients with this variant further emphasizing the importance of assessing impacts beyond catalytic activity when evaluating genotype-phenotype relationships in DADA2.

Inflammatory diseases in hematology: a review.

Hematopoietic cells are instrumental in generating and propagating protective inflammatory responses to infection or injury. However, excessive inflammation contributes to many diseases of the blood, bone marrow, and lymphatic system. We review three clinical categories of hematological inflammatory diseases in which recent clinical and translational advances have been made. The first category is monogenic inflammatory diseases. Genotype-driven research has revealed that previously mysterious diseases with protean manifestations are characterized by mutations that may be germline (e.g., deficiency of ADA2 or GATA2 deficiency) or somatic [e.g., vacuoles, enzyme E1, X-linked, autoinflammatory, somatic (VEXAS) syndrome]. The second category is the cytokine storm syndromes, including hemophagocytic lymphohistiocytosis, and Castleman disease. Cytokine storm syndromes are characterized by excessive production of inflammatory cytokines including interleukin-6 and interferon-γ, causing end-organ damage and high mortality. Finally, we review disorders associated with monoclonal and polyclonal hypergammaglobulinemia. The serum protein electrophoresis (SPEP) is typically ordered to screen for common diseases such as myeloma and humoral immunodeficiency. However, monoclonal and polyclonal hypergammaglobulinemia on SPEP can also provide important information in rare inflammatory diseases. For example, the autoinflammatory disease Schnitzler syndrome is notoriously difficult to diagnose. Although this orphan disease has eluded precise genetic or histological characterization, the presence of a monoclonal paraprotein, typically IgM, is an obligate diagnostic criterion. Likewise, polyclonal hypergammaglobulinemia may be an important early, noninvasive diagnostic clue for patients presenting with rare neoplastic diseases such as Rosai-Dorfman disease and angioimmunoblastic T-cell lymphoma. Applying these three categories to patients with unexplained inflammatory syndromes can facilitate the diagnosis of rare and underrecognized diseases.

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.

P295 Establishing adenosine deaminase 2 activity in a cohort of patients with large vessel vasculitis

Abstract Background/Aims Deficiency of adenosine deaminase 2 (DADA2) leads to a broad phenotype; some patients develope vasculitis and strokes, and others have predominantly haematological manifestations. Small, medium and large vessel vasculitis has been described. In contrast, plasma ADA2 activity is elevated in inflammatory conditions including systemic lupus erythematosus and systemic juvenile idiopathic arthritis with macrophage activation syndrome. The role of ADA2 and how its deficiency associates with the vasculitides is not well understood. Using a well-characterised large vessel vasculitis cohort, we sought to establish the potential role of ADA2 activity. Methods ADA2 activity was measured in adults with Takayasu arteritis (TA), large vessel giant cell arteritis (LV-GCA), intracranial vasculitis (IV) and healthy control (HC) subjects using a coupled spectrophotometric assay. Plasma from 11 patients with genotyped DADA2 and 10 patients heterozygous for pathogenic variants in ADA2 were used to define thresholds for deficiency and carrier status respectively (DADA2 activity 0 - 0.90 U/L, ADA2 carrier activity 2.02 - 10.62 U/L). Activity levels above the upper limit of normal (ULN) were defined as > 99th percentile of the HC activity (30.3U/L). To assess potential associations with TA disease status, ADA2 was measured prospectively in matched active and remission samples. TA disease activity was determined as active, grumbling or stable using clinical and radiological features, physician impression, CRP, ESR and Indian Takayasu clinical Activity Score (ITAS). Results No patients had deficient ADA2 activity while 7 subjects had activity within the carrier range (1 HC [1.9%], 5 TA [3.7%], 1 LV-GCA [2.3%]). Compared to HC levels (17.43 [14.11 - 20.78] U/L), activity in the TA group was significantly increased (TA 19.68U/L, p = 0.0061), while LV-GCA and IV were not significantly different. In 20 cases, activity exceeded the ULN; 16 TA (11.9%, p = 0.044; 4 active, 2 grumbling, 10 stable) and 4 LV-GCA (9.1%, ns). In TA, there was a positive correlation between ADA2 activity and ESR (Spearman R = 0.2863, p = 0.0009) but not with CRP or ITAS score. Subgroup analysis revealed ADA2 activity was most prominently elevated in the stable group relative to HCs (TA stable 20.54 U/L [8.08 - 48.66], median +17.8%, p = 0.0006), but not with active or grumbling disease. Consistent with this, prospective analysis demonstrated a significant increase in ADA2 activity in remission vs active disease (p = 0.024), with activity increasing in 18 (62%) patients achieving remission. Conclusion There were no cases of ADA2 deficiency in this cohort. Consistent with other inflammatory conditions, ADA2 activity was elevated in TA compared to HC subjects. Surprisingly, increased ADA2 activity was linked to stable TA in both cross-sectional and prospective analyses. This may suggest a potential role of ADA2 enzyme activity in vascular repair and regrowth - possibly tying in with known elevated levels of ADA2 activity in growing children. Disclosure A. Porter: None. R. Maughan: None. C. Pericleous: None. A. Kiprianos: None. H. Jee: None. P. Lee: None. T. Youngstein: None. J. Mason: None.

A Novel LC-MS/MS-Based Method for the Diagnosis of ADA2 Deficiency from Dried Plasma Spot.

Adenosine Deaminase 2 Deficiency (DADA2) (OMIM: 607575) is a monogenic, autoinflammatory disease caused by the loss of functional homozygous or heterozygous mutations in the ADA 2 gene (previously CECR1, Cat Eye Syndrome Chromosome Region 1). A timely diagnosis is crucial to start Anti-TNF therapies that are efficacious in controlling the disease. The confirmation of DADA2 is based on DNA sequencing and enzymatic assay. It is, thus, very important to have robust and reliable assays that can be rapidly utilized in specialized laboratories that can centralize samples from other centers. In this paper, we show a novel enzymatic assay based on liquid chromatography-tandem mass spectrometry that allows the accurate determination of the ADA2 enzyme activity starting from very small amounts of plasma spotted on filter paper (dried plasma spot). The method allows significantly distinguishing healthy controls from affected patients and carriers and could be of help in implementing the diagnostic workflow of DADA2.

Arteriopathy in pediatric stroke: an underestimated clinical entity.

Pediatric arterial ischemic stroke (AIS), which was thought to be a rare disorder, is being increasingly recognized as an important cause of neurological morbidity, thanks to new advances in neuroimaging. The aim of this study was to review the main etiologies of stroke due to arteriopathy in children. Using a series of cases from our institution, we addressed its epidemiological aspects, physiopathology, imaging findings from CT, MR angiography, MR conventional sequences and MR DWI, and nuclear medicine findings. Through discussion of the most recent classification for childhood AIS (Childhood AIS Standardized Classification and Diagnostic Evaluation, CASCADE), we propose a modified classification based on the anatomical site of disease, which includes vasculitis, varicella, arterial dissection, moyamoya, fibromuscular dysplasia, Takayasu's arteritis and genetic causes (such as ACTA-2 mutation, PHACE syndrome and ADA-2 deficiency). We have detailed each of these separately. Conclusions: Prompt recognition of AIS and thorough investigation for potential risk factors are crucial for a better outcome. In this scenario, neurovascular imaging plays an important role in diagnosing AIS and identifying children at high risk of recurrent stroke.

Dysregulation in B‐cell responses and T follicular helper cell function in ADA2 deficiency patients

Adenosine deaminase 2 deficiency (DADA2) is an autoinflammatory disease characterized by inflammatory vasculopathy, early strokes associated often with hypogammaglobulinemia. Pure red cell aplasia, thrombocytopenia, and neutropenia have been reported. The defect is due to biallelic loss of function of ADA2 gene, coding for a protein known to regulate the catabolism of extracellular adenosine. We therefore investigated immune phenotype and B- and T-cell responses in 14 DADA2 patients to address if ADA2 mutation affects B- and T-cell function. Here, we show a significant decrease in memory Bcells, in particular class switch memory, and an expansion of CD21low Bcells in DADA2 patients. In vitro stimulated B lymphocytes were able to secrete nonfunctional ADA2 protein, suggesting a cell intrinsic defect resulting in an impairment of B-cell proliferation and differentiation. Moreover, CD4+ and CD8+ Tcells were diminished; however, the frequency of circulating T follicular helper cells was significantly increased but they had an impairment in IL-21 production possibly contributing to an impaired Bcell help. Our findings suggest that ADA2 mutation could lead to a B-cell intrinsic defect but also to a defective Tfh cell function, which could contribute to the immunodeficient phenotype reported in DADA2 patients.

Clusters in Pediatric Rheumatic Diseases.

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. 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.

36. All headaches are not GCA

IntroductionVasculitis is a heterogeneous group of autoimmune disorders having multisystem involvement. In many cases, the neurological disorders have an atypical clinical course or even an early onset, and the healthcare professionals should be aware of them.Case descriptionWe report a case of 57-year-old Asian male without any significant past medical history admitted under the urology department. He had presented with abdominal pain and fever and was being treated for presumptive pyelonephritis (on antibiotics). He was referred to rheumatology when he developed severe unilateral headache on right side with significant scalp tenderness. Headache involved temporal and fronto-parietal-occipital area with no jaw claudication or any significant visual disturbance. There was no limb claudication or polymyalgia symptoms. On examination he had new onset hypertension (BP:174/94mmHg), rest of the systemic examination was normal with no bruit. Musculoskeletal and skin examination was normal.Investigations included CRP of 204, hemoglobin 133, white cell count 15.2 (neutrophils: 12.06), creatinine 118 (eGFR 59). Liver function: normal. Urine dip: Normal and blood/urine culture: negative. Immunological profile and viral screen was negative. Urgent CT head was done for severe headache which was normal. Patient was referred to rheumatology with provisional diagnosis of giant cell arteritis due to headache and raised inflammatory markers. On reviewing his CT abdomen, the renal parenchyma showed symmetrical well demarcated bilateral involvement which was more in favor of renal infarct rather than pyelonephritis. CT angiography of abdomen was requested which showed multiple vessel involvement including mesenteric artery and bilateral renal arteries with beaded appearance and stenosis. MR angiogram showed 6mm aneurysm of PICA with stenosis of P1 segment of PCA. Currently he is being screened for ADA2 deficiency. During his stay his renal function deteriorated, not responding previously to antibiotics. He was started on methylprednisolone pulse and antibiotics stopped in view of worsening liver function. On day 3 of methylprednisolone pulse he had significant improvement of his headache with stabilization of renal and liver function. Our plan is to start him on steroid sparing therapy based on the ADA2 levels.DiscussionThe classification of vasculitis is still unsatisfactory as the patho-genetic mechanisms have not been fully understood. Existing criteria classify based on predominant vessel involvement but there is still some overlap between them. The prevalence of CNS involvement in medium vessel vasculitis ranges as widely as 2-10% and does not usually occur until late in the course of the disease. The most commonly reported CNS manifestation is diffuse encephalopathy, followed in frequency by focal deficits and seizures. Intracranial aneurysms are rare with around 15 reported cases usually multiple and located in supra- as well as infra-tentorial compartments. Most of the cases presented with subarachnoid or parenchymal hemorrhage. Treatment guidelines are still not clear and most are treated conservatively by medical management. Repeat hemorrhages or re-bleed in spite of medical treatment have also been reported Deficiency of ADA2 (DADA2) has been recently recognized first molecularly described monogenic vasculitis having biallelic hypomorphic mutation in ADA2 gene. CNS involvement is one of the main features of DADA2 which presents with a wide spectrum of clinical manifestations ranging from systemic inflammation to cutaneous or visceral PAN like vasculopathy and early onset stroke.Our patient had presented with primary CNS and renal involvement with impending rupture aneurysm. Timely control of inflammation is pertinent in such cases with remission induction and maintenance to prevent stroke. Although cyclophosphamide is still used in such cases DADA2 usually require anti-TNF therapy. Our patient had good response to primary steroid therapy.Key learning pointsAcute GCA-like neurological presentation of medium vessel vasculitis with cerebral involvement is rare. If not recognised in a timely fashion, it can lead to sub-arachnoid haemorrhage which is the most common presentation of such cases. DADA2 is a recently recognised entity that presents with stroke and vasculitis/vasculopathy and responds to anti-TNF therapy.Conflicts of interestThe authors have declared no conflicts of interest.

YOUTH HYPERTENSION ASSOCIATED WITH ADA2 DEFICIENCY. ABOUT THREE CASES

Objective: Youth hypertension is often secondary. The deficiency of Adenosine Deaminase 2 (DADA2) is a new autoinflammatory disease. the DADA2 was first described associated with clinical manifestations of a nodosa polyarthéritis and early- Onset stroke. Clinically, DADA2 has three main phenotypes, the inflammatory vascular phenotype, hematological form and Immunological form. We report the case of three members of the same family with hypertension since their early ages. Design and method: This is a retrospective study of case series of patients associating a hypertension of the young and an ADA2 deficiency. The patients are from the same family, Resulting from a 2nd degree consanguineous marriage. Results: The patient H.F born in 1998. HF had recurrent fever, arthralgia since the age of 2 years, hypertension since the age of 6 years, he is stable on treatment with losartan 50 mg and nicardipine 100 mg / day. In March 2016 the patient had headache, dizziness and abdominal pain, MRI exploration found an appearance of cerebral vasculitis with the presence of numerous demyelinating lesions. In 2018, The search for the gene mutation of ADA2 was positive with the presence of the mutation c. [139G> A]; [139G> A] p [Gly47Arg]; [Gly47Arg]. the same mutation was found in his 10-year-old brother H.A. during the family survey we found that our patient has a brother H.Y. H.Y had a similar symptomology but less severe from a young age. he currently has a urticariaine reaction to cold and hypertension. our patient had a brother H.F born in 1984. H.F had a stroke at which a hypertension was diagnosed. This patient had presented kidney failure dialysis at the age of 16 years died at the age of 17 years. the diagnosis of DADA2 in the two brothers is retained in front of the similar clinical symptomatology and the family context. Conclusions: In our series, HTA is associated with DADA2 in three patients. DADA2-associated HTA is particularly common in children and may be associated with complications such as early stroke, cerebral vasculitis and renal failure

Variable Clinical Phenotypes and Relation of Interferon Signature with Disease Activity in ADA2 Deficiency.

An upregulation of type I interferon (IFN) stimulated genes [IFN score (IS)] was described in patients with adenosine deaminase 2 deficiency (DADA2). We describe the clinical course of 5 such patients and the role of IS as a marker of disease activity and severity. Expression levels of IS were determined by quantitative real-time PCR. Five white patients were identified as carrying CECR1 mutations. The IS before treatment was elevated in 4 out of 5 patients and decreased after treatment. Our data confirm the high variability of DADA2 and suggest type I IS as a biomarker of disease activity.

The Genetic Landscape of Diamond-Blackfan Anemia

Diamond-Blackfan anemia (DBA) is a rare bone marrow failure disorder that affects 7 out of 1,000,000 live births and has been associated with mutations in components of the ribosome. In order to characterize the genetic landscape of this heterogeneous disorder, we recruited a cohort of 472 individuals with a clinical diagnosis of DBA and performed whole-exome sequencing (WES). We identified relevant rare and predicted damaging mutations for 78% of individuals. The majority of mutations were singletons, absent from population databases, predicted to cause loss of function, and located in 1 of 19 previously reported ribosomal protein (RP)-encoding genes. Using exon coverage estimates, we identified and validated 31 deletions in RP genes. We also observed an enrichment for extended splice site mutations and validated their diverse effects using RNA sequencing in cell lines obtained from individuals with DBA. Leveraging the size of our cohort, we observed robust genotype-phenotype associations with congenital abnormalities and treatment outcomes. We further identified rare mutations in seven previously unreported RP genes that may cause DBA, as well as several distinct disorders that appear to phenocopy DBA, including nine individuals with biallelic CECR1 mutations that result in deficiency of ADA2. However, no new genes were identified at exome-wide significance, suggesting that there are no unidentified genes containing mutations readily identified by WES that explain >5% of DBA-affected case subjects. Overall, this report should inform not only clinical practice for DBA-affected individuals, but also the design and analysis of rare variant studies for heterogeneous Mendelian disorders.