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.

A Successful Infliximab Treatment of a Pediatric Case of Severe Polyarteritis Nodosa With a Cerebral Infarction and a Decreased Adenosine Deaminase 2 Activity

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis common in males over 50 years of age that causes various organ symptoms. In recent years, it has become important to distinguish deficiency of adenosine deaminase 2 (DADA2) from childhood-onset PAN. A 13-year-old girl was urgently transferred to our hospital with sudden weakness in her right upper and lower limbs. The National Institutes of Health Stroke Scale (NIHSS) was 8. Plain MRI of the brain indicated high-signal areas in the right caudate nucleus, internal capsule, and left basal ganglia when applying T2-weighted, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI); and low signals in the same regions in an apparent diffusion coefficient (ADC) map. It demonstrated inflammatory demyelinating disease of the central nervous system or multiple cerebral infarctions attributable to vasculitis, and it is difficult to differentiate between them based on image findings alone, and cannot be determined without following the clinical course. Hence, we treated with steroid therapy, which is effective for both conditions. Although the paralysis was alleviated, an MRI of the brain reperformed on day 7 revealed expansion of the lesion with contrast enhancement in the feeding area of the left lateral striatal artery, a high signal in DWI, and a low signal in an ADC map. Based on the clinical and radiological findings, we diagnosed a cerebral infarction attributable to vasculitis. Contrast computed tomography (CT) of her chest and abdominal CT angiography revealed that she met the diagnostic criteria for PAN, and adenosine deaminase 2 (AD2) activity level was low. The patient was treated with steroids combined with azathioprine and cyclophosphamide but three weeks after discharge developed a new cerebral infarction in the right basal ganglia. We commenced infliximab; no recurrence of cerebral infarction has been noted. The low AD2 activity may explain the intractable atypical course of this case. Further studies are needed to reveal the role of AD2 in patients with residual enzyme activity and reevaluation of the PAN diagnostic criteria is essential.

Deficiency of adenosine deaminase 2: a challenging differential diagnosis of polyarteritis nodosa

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive disorder that was first described in 2014. It is a monogenic disease that is caused by loss-of-function variants in the ADA2 gene. Deficiency of adenosine deaminase 2 involves small- and medium-sized vessels and its clinical presentations include polyarteritis nodosa (PAN)-like features such as livedoid rash, early-onset stroke, hypogammaglobulinemia, hematological abnormalities, and systemic inflammation. Early diagnosis and treatment of DADA2 are crucial as the clinical features could be potentially life-threatening but might be treatable. The first-line treatment of choice in DADA2 is tumor necrosis factor α inhibitors. We aimed to provide an overview of the known pathophysiology, clinical presentations, diagnosis, and treatment of DADA2. A clearer knowledge of DADA2 may help to better diagnose, manage, and improve the clinical outcome of DADA2 patients. However, further studies are required to investigate the genotype-phenotype associations and exact pathophysiology of DADA2.

A Unique Case of Deficiency of Adenosine Deaminase 2 Single in a Young Adult Patient

Deficiency of adenosine deaminase 2 (DADA2) is a rare monogenic disease caused by mutations in the adenosine deaminase 2 gene (ADA2). It is characterized by a wide range of manifestations, including systemic inflammation and vasculopathy, early onset stroke (ischemic or hemorrhagic), immunodeficiency, and bone marrow failure. The diagnosis of DADA2 is confirmed by pathogenic mutations in ADA2 or low ADA2 enzymatic activity in the patient. In this study, we present a case of a 24-year-old Saudi male who was admitted with symptomatic anemia, lightheadedness, exertional symptoms, and a history of fever (38.1 C) for one week. Laboratory tests revealed normocytic normochromic anemia, leucopenia, lymphopenia, and neutropenia-autoimmune profile: low C3 and positive anti-ds DNA. The genetic testing revealed two Pathogenic variants, which were identified in ADA2. The diagnosis of DADA2 was made, and the patient received subcutaneous adalimumab 40 mg every two weeks. At the follow-up after one month, he showed improvement in fever, rash, and C-reactive protein (CRP) from (6 to 0.65). In conclusion, we present one of the first cases in Saudi Arabia of an adult patient diagnosed with DADA2 with a unique gene mutation. Adult-onset patients with DADA2 usually have a vague presentation and a relatively narrower phenotype range of symptoms which produce additional challenges for the physician to add DADA2 to the list of differentials. We suggest further studies investigate the genotype-phenotype association, possible clinical presentation, and the development of curative treatments for those cases.

Case Report: Interindividual variability and possible role of heterozygous variants in a family with deficiency of adenosine deaminase 2: are all heterozygous born equals?

Deficiency of adenosine deaminase 2 (DADA2) is a rare systemic autoinflammatory disease, typically with autosomal recessive inheritance, usually caused by biallelic loss of function mutations in the ADA2 gene. The phenotypic spectrum is broad, generally including fever, early-onset vasculitis, stroke, and hematologic dysfunction. Heterozygous carriers may show related signs and symptoms, usually milder and at an older age. Here we describe the case of two relatives, the proband and his mother, bearing an ADA2 homozygous pathogenic variant, and a heterozygous son. The proband was a 17-year-old boy with intermittent fever, lymphadenopathies, and mild hypogammaglobulinemia. He also had sporadic episodes of aphthosis, livedo reticularis and abdominal pain. Hypogammaglobulinemia was documented when he was 10 years old, and symptoms appeared in his late adolescence. The mother demonstrated mild hypogammaglobulinemia, chronic pericarditis since she was 30 years old and two transient episodes of diplopia without lacunar lesions on MRI. ADA2 (NM_001282225.2) sequencing identified both mother and son as homozygous for the c.1358A>G, p.(Tyr453Cys) variant. ADA2 activity in the proband and the mother was 80-fold lower than in the controls. Clinical features in both patients improved on anti-tumor necrosis factor therapy. An older son was found to be heterozygous for the same mutation post-mortem. He died at the age of 12 years due to a clinical picture of fever, lymphadenitis, skin rash and hypogammaglobulinemia evolving toward fatal multiorgan failure. Biopsies of skin, lymph nodes, and bone marrow excluded lymphomas and vasculitis. Despite being suspected of symptomatic carrier, the contribution of an additional variant in compound heterozygosity, or further genetic could not be ruled out, due to poor quality of DNA samples available. In conclusion, this familiar case demonstrated the wide range of phenotypic variability in DADA2. The search for ADA2 mutations and the assessment of ADA2 activity should be considered also in patients with the association of hypogammaglobulinemia and inflammatory conditions, also with late presentation and in absence of vasculitis. Furthermore, the clinical picture of the deceased carrier suggests a possible contribution of heterozygous pathogenic variants to inflammation.

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.

Single-cell profiling of T lymphocytes in deficiency of adenosine deaminase 2

Deficiency of adenosine deaminase 2 (DADA2) is a monogenic vasculitis syndrome caused by autosomal-recessive loss-of-function mutations in the ADA2 gene (previously known as CECR1). Vasculitis, vasculopathy, and inflammation are dominant clinical features of this disease; the spectrum of manifestations includes immunodeficiency and lymphoproliferation as well as hematologic manifestations. ADA2 is primarily secreted by stimulated monocytes and macrophages. Aberrant monocyte differentiation to macrophages and neutrophils are important in the pathogenesis of DADA2, but little is known about T lymphocytes in this disease. We performed combined single-cell RNA sequencing and single-cell TCR sequencing in order to profile T cell repertoires in 10 patients with DADA2. Although there were no significant alterations of T cell subsets, we observed activation of both CD8⁺ and CD4⁺ T cells. There was no clonal expansion of T cells: most TCRs were expressed at basal levels in patients and healthy donors. TCR usage was private to individual patients and not disease specific, indicating as unlikely a common pathogenic background or predisposition to a common pathogen. We recognized activation of IFN pathways as a signature of T cells and STAT1 as a hub gene in the gene network of T cell activation and cytotoxicity. Overall, T cells in DADA2 patients showed distinct cell-cell interactions with monocytes, as compared with healthy donors, and many of these ligand-receptor interactions likely drove up-regulation of STAT1 in both T cells and other immune cells in patients. Our analysis reveals previously undercharacterized cell characteristics in DADA2.

Analysis of deficiency of adenosine deaminase 2 pathogenesis based on single-cell RNA sequencing of monocytes

Deficiency of adenosine deaminase 2 (DADA2) is a rare autosomal recessive disease caused by loss-of-function variants in the ADA2 gene. DADA2 typically presents in childhood and is characterized by vasculopathy, stroke, inflammation, immunodeficiency, as well as hematologic manifestations. ADA2 protein is predominantly present in stimulated monocytes, dendritic cells, and macrophages. To elucidate molecular mechanisms in DADA2, CD14⁺ monocytes from 14 patients and 6 healthy donors were analyzed using single-cell RNA sequencing (scRNA-seq). Monocytes were purified by positive selection based on CD14 expression. Subpopulations were imputed from their transcriptomes. Based on scRNA-seq, monocytes could be classified as classical, intermediate, and nonclassical. Further, we used gene pathway analytics to interpret patterns of up- and down-regulated gene transcription. In DADA2, the frequency of nonclassical monocytes was higher compared with that of healthy donors, and M1 macrophage markers were up-regulated in patients. By comparing gene expression of each monocyte subtype between patients and healthy donors, we identified upregulated immune response pathways, including IFNα/β and IFNγ signaling, in all monocyte subtypes. Distinctively, the TNFR2 noncanonical NF-κB pathway was up-regulated only in nonclassical monocytes. Patients' plasma showed increased IFNγ and TNFα levels. Our results suggest that elevated IFNγ activates cell signaling, leading to differentiation into M1 macrophages from monocytes and release of TNFα. Immune responses and more general response to stimuli pathways were up-regulated in DADA2 monocytes, and protein synthesis pathways were down-regulated, perhaps as stress responses. Our identification of novel aberrant immune pathways has implications for therapeutic approaches in DADA2 (registered at clinicaltrials.gov NCT00071045).

[Corrigendum] Role of adenosine deaminase 2 gene variants in pediatric deficiency of adenosine deaminase 2: A structural biological approach

Following the publication of the above article on modeling variants of adenosine deaminase 2 (ADA2), previously identified by Gibson et al [Kristen M. Gibson, Kimberly A. Morishita, Paul Dancey, Paul Moorehead, Britt Drögemöller, Xiaohua Han, Jinko Graham, Robert E. W. Hancock, Dirk Foell, Susanne Benseler, Rashid Luqmani, Rae S. M.Yeung, Susan Shenoi, Marek Bohm, Alan M. Rosenberg, Colin J. Ross, David A. Cabral and Kelly L. Brown: Identification of novel adenosine deaminase 2 gene variants and varied clinical phenotype in pediatric vasculitis. Arthritis Rheumatol 71: 1747‑1755, 2019], (reference 18 in the article), Dr. Kelly L. Brown, corresponding author of the Gibson et al article, drew to the authors' attention possible discrepancies identified therein. Upon examining the matters raised by Dr. K. Brown, the authors wish to publish a corrigendum for this article, and the following textual changes are required to the main text. The authors noted that it was not accurate to have referred to the p.Gly47Arg mutation as being 'novel' when this mutation was being specifically referred to, so the word 'novel' should have been omitted from the sentence in the abstract starting on line 17: 'This led to suggestions that the mutations found may affect the formation/stability of the homodimer or may influence the activity of the enzyme (15)'. However, Gibson et al in their paper stated that ADA2 variant with the mutation Gly47Arg in sera from homozygous individuals was a dimer (18). Also, the word 'novel' should not have been included in the title of Fig. 3, and this should have appeared as follows: 'Figure 3. The DADA2‑associated mutation G47R in the ADA2 structure', and also, for consistency, the titles of Figs. 4 and 5 should have been written as 'Figure 4. The DADA2‑associated novel mutation R34W in the ADA2 structure' and 'Figure 5. The DADA2‑associated novel mutation A357T in the ADA2 structure'. The authors would like to add that the p.Arg34Trp variant's association with DADA2 has been previously identified in a paper by Kaljas et al: Human adenosine deaminases ADA1 and ADA2 bind to different subsets of immune cells. Kaijas Y, Liu C, Skaldin M, Wu C, Zhou Q, Lu Y, Aksentijevich I and Zavialow AV: Cell Mol Life Sci 74: 550‑570, 2017. In addition, the novel rare mutation identified by Gibson et al as Arg9Trp associated with DADA2 lies in the signal peptide [stated by the authors as Arg8Trp because Met#1 (ATG start codon) is not included in the protein numbering] and is not obviously included in the three‑dimensional structure, and therefore the authors did not deal with it. So, the sentence in the Abstract starting on line 19 should have been written as follows: 'It was thus concluded that the Gly47Arg mutation affects the position and interaction of the dimer‑associated HN1 helical structure'. All references of Arg8Trp in the text, when referred to the Gibson et al article, should be changed to Arg9Trp as referred therein so as not to cause confusion. Finally, in the legend for Fig. 2, 'His358' should have been written as 'His356' (line 3), and for the purposes of clarification, where 'at the next Asn352 (2)' was written at the end of the same sentence, this text should be changed to 'at the neighboring glycosylated Asn378 [Asn352 in (2)]'. Similarly, on p. 880, the sentence at the end of the penultimate paragraph of the Results section should have been written as follows: 'This disruption could be transmitted to the neighboring His356 coordinated to the metal ion or affect the confirmed glycosylation at the neighboring glycosylated Asn378 [Asn352 in (2)]'. The authors thank Dr. K. L. Brown for drawing these matters to their attention, and emphasize that the resultant corrections and clarifications do not alter either the results or the main conclusions reported in the paper. [the original article was published in Molecular Medicine Reports 21: 876‑882, 2020; DOI: 10.3892/mmr.2019.10862].

Case Report: An Adult Patient With Deficiency of Adenosine Deaminase 2 Resembled Unilateral Frosted Branch Angiitis

Purpose: Deficiency of adenosine deaminase 2 (DADA2) is a rare autosomal recessive systemic autoinflammatory disorder. We describe a rare case of an adult patient with DADA2 who presented with unilateral frosted branch angiitis (FBA) combined with branch retinal vein occlusion and panuveitis.

Method: This paper is a clinical case report.

Results: A 31-year-old male patient complained of blurred vision in his right eye for 2 days. His fundus examination showed FBA combined with branch retinal vein occlusion and panuveitis. He had a medical history of intermittent and recurrent fever, skin rash and aphthous ulcer for 5 years, and lacunar infarction for 1 month. Laboratory examinations showed hypogammaglobulinemia and mild prolonged activated partial thromboplastin time (APTT). Brain magnetic resonance imaging (MRI) revealed old lacunar infarction in the right basal ganglia and the lateral ventricle and fresh lacunar infarction in the right pons, respectively. The perivascular sheathing of FBA and macular edema were resolved after steroid administration and treatment of intravitreal anti-VEGF injection. During the period of follow-up, the patient subsequently suffered from recurrence of strokes, abnormality of coagulation function, sudden hearing loss of the left ear, and diplopia. His gene sequencing results demonstrated several deletion mutations in ADA2, and the diagnosis of DADA2 was eventually confirmed.

Conclusions: FBA represents a very rare ocular feature of DADA2 and may in some cases be the presenting manifestation. Therefore, ophthalmologists need to be aware of this rare autoinflammatory disease.

Spectrum of Systemic Auto-Inflammatory Diseases in India: A Multi-Centric Experience

Background: Systemic autoinflammatory diseases (SAID) are rare inherited disorders involving genes regulating innate immune signaling and are characterized by periodic or chronic multi-systemic inflammation.

Objective: To describe spectrum of clinical, immunological, molecular features, and outcomes of patients with SAID in India.

Methods: Request to share data was sent to multiple centers in India that are involved in care and management of patients with Inborn Errors of Immunity. Six centers provided requisite data that were compiled and analyzed.

Results: Data on 107 patients with SAID were collated—of these, 29 patients were excluded due to unavailability of complete information. Twelve patients (15%) had type 1 interferonopathies, 21 (26%) had diseases affecting inflammasomes, 30 patients (41%) had non-inflammasome related conditions and 1five patients (19%) had Periodic Fever, Aphthous Stomatitis, Pharyngitis, Adenitis (PFAPA). Type1 interferonopathies identified in the cohort included patients with Deficiency of Adenosine Deaminase 2 (DADA2) (six patients; five families); STING-associated vasculopathy infantile-onset (SAVI) (three patients, one family); Spondyloenchondro-dysplasia with Immune Dysregulation (SPENCD) (two patients). Diseases affecting inflammasomes include Mevalonate Kinase Deficiency (eight patients); Cryopyrin-Associated Periodic Syndromes (CAPS) (seven patients); NLR Family, Pyrin domain-containing 12 (NLRP12) (two patients); Familial Mediterranean fever (FMF) (two patients); Autoinflammation and PLCG₂-associated antibody deficiency and immune dysregulation (APLAID) (two patients). TNF receptor-associated periodic syndrome (TRAPS) (three patients); A20 haploinsufficiency (four patients); Deficiency of Interleukin 1 Receptor Antagonist (DIRA) (two patients) were categorized as non-inflammasome related conditions. There were significant delays in diagnosis Corticosteroids and other immunosuppressive agents were used for treatment as anti-IL-1 drugs and other biological agents were and still are not available in India. Eight (16.3%) patients had so far succumbed to their illness.

Conclusions: This is the first nationwide cohort of patients with SAID from India. Clinical manifestations were diverse. Overlapping of clinical features with other relatively common rheumatological disorders often resulted in delays in diagnosis. More nationwide efforts are needed to enhance awareness of SAID among health care professionals and there is an urgent need to make targeted immunotherapies universally available.

Atypical phenotype of an old disease or typical phenotype of a new disease: deficiency of adenosine deaminase 2

Çakan M, Aktay-Ayaz N, Karadağ ŞG, Tahir-Turanlı E, Stafstrom K, Bainter W, Geha RS, Chou J. Atypical phenotype of an old disease or typical phenotype of a new disease: deficiency of adenosine deaminase 2. Turk J Pediatr 2019; 61: 413-417. Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive autoinflammatory disorder caused by mutations in CECR1 (cat eye syndrome chromosome region, canditate 1) gene, which encodes the enzyme adenosine deaminase 2 necessary for endothelial cell survival and function. The diversity of the clinical phenotypes associated with DADA2 include polyarteritis nodosa-like vasculitic features, early-onset stroke, mild to severe immunodeficiency and cytopenias. The diagnosis of the disease may be difficult due to complex clinical phenotype. Herein, we present a case of DADA2 presenting with vasculitis, amarousis fugax, gastrointestinal bleeding and silent lacunar infarct successfully treated with etanercept.

Deficiency of Adenosine Deaminase 2 (DADA2): Hidden Variants, Reduced Penetrance, and Unusual Inheritance

PURPOSE

Deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive disorder that manifests with fever, early-onset vasculitis, strokes, and hematologic dysfunction. This study aimed to identify disease-causing variants by conventional Sanger and whole exome sequencing in two families suspected to have DADA2 and non-confirmatory genotypes. ADA2 enzymatic assay confirmed the clinical diagnosis of DADA2. Molecular diagnosis was important to accurately identify other family members at risk.

METHODS

We used a variety of sequencing technologies, ADA2 enzymatic testing, and molecular methods including qRT-PCR and MLPA.

RESULTS

Exome sequencing identified heterozygosity for the known pathogenic variant ADA2: c.1358A>G, p.Tyr453Cys in a 14-year-old female with a history of ischemic strokes, livedo, and vasculitis. No second pathogenic variant could be identified. ADA2 enzymatic testing in combination with quantitative RT-PCR suggested a loss-of-function allele. Subsequent genome sequencing identified a canonical splice site variant, c.-47+2T>C, within the 5'UTR of ADA2. Two of her unaffected siblings were found to carry the same two pathogenic variants. A homozygous 800-bp duplication comprising exon 7 of ADA2 was identified in a 5-year-old female with features consistent with Diamond-Blackfan anemia (DBA). The duplication was missed by Sanger sequencing of ADA2, chromosomal microarray, and exome sequencing but was detected by MLPA in combination with long-read PCR sequencing. The exon 7 duplication was also identified in her non-symptomatic father and younger sister.

CONCLUSIONS

ADA2 pathogenic variants may not be detected by conventional sequencing and genetic testing and may require the incorporation of additional diagnostic methods. A definitive molecular diagnosis is crucial for all family members to make informed treatment decisions.

Early-onset stroke, polyarteritis nodosa (PAN), and livedo racemosa

KEY TEACHING POINTS.