Polyarteritis nodosa and deficiency of adenosine deaminase 2 - Shared genealogy, generations apart

Deficiency of adenosine deaminase 2: a genetic autoinflammatory disorder mimicking childhood polyarteritis nodosa

A girl in the early adolescent age group presented with multisystem manifestations in the form of periodic fever, recurrent abdominal pain, hypertension, seizure, skin lesions over the chest and gangrene over the left ring and middle fingertips. Her condition had remained undiagnosed for 11 years. On evaluation, she had features of polyarteritis nodosa (PAN) (multiple aneurysms, symmetric sensorimotor peripheral neuropathy, superficial ulcers, digital necrosis, myalgia, hypertension and proteinuria). As childhood PAN is a phenocopy of adenosine deaminase 2 with a different management strategy, whole-exome sequencing was performed, which revealed a pathogenic variant in ADA2 gene. The child was treated with TNF alpha inhibitors and showed improvement in the Paediatric Vasculitis Activity Score. The paper highlights the gratifying consequences of correct diagnosis with disease-specific therapy that ended the diagnostic odyssey, providing relief to the patient from debilitating symptoms and to the family from the financial burden of continued out-of-pocket health expenditure.

Cutaneous vasculitis in autoinflammatory diseases

Autoinflammatory diseases (AIDs) characterized by recurrent episodes of localized or systemic inflammation are disorders of the innate immune system. Skin lesions are commonly found in AIDs and cutaneous vasculitis can coexist with AIDs and even present as the most striking feature. This review aims to focus on the frequent cutaneous vasculitis association in three monogenic AIDs including familial Mediterranean fever (FMF), deficiency of adenosine deaminase type 2 (DADA2), and the recently identified adult-onset VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Cutaneous vasculitis in FMF is characterized by: (1) small-vessel vasculitis similar to IgA vasculitis with palpable purpura but increased intussusception complication and less vascular IgA deposit, and (2) cutaneous arteritis-like vasculitis presenting as subcutaneous nodules most often with higher glomerular involvement. DADA2 has a wide spectrum of clinical presentations ranging from fatal systemic vasculitis with multiple strokes, especially in pediatric patients, to limited cutaneous disease in middle-aged patients. DADA2 shares similar clinical and histopathological features with polyarteritis nodosa (PAN). As a result, DADA2 is commonly initially misdiagnosed as childhood PAN. Livedo racemosa reveals the most common cutaneous manifestation of cutaneous vasculitis in patients with DADA2. VEXAS syndrome is a life-threatening disease. A diagnosis of VEXAS syndrome should be strongly considered or could be made in patients with skin lesions characterized by Sweet syndrome-like eruption, livedo racemosa, concomitant relapsing polychondritis, deep venous thrombosis, pulmonary involvement, and progressive hematologic abnormalities such as myelodysplastic syndrome with a unique finding of cytoplasmic vacuoles in myeloid and erythroid precursor cells from bone marrow aspirate smear. As skin involvement is common in AIDs and may present as the most frequent manifestation, especially in DADA2 (70% to 90%) and VEXAS syndrome (83% to 91%), dermatologists play a crucial role in contributing to the early diagnosis of these AIDs with early initiation of the appropriate therapy to avoid progressing fatal outcomes.

Overview of Vasculitides in Adults

Vasculitis is characterized by the inflammation of blood vessels. Vasculitides refers to the different forms of vasculitis, often classified according to the size of the blood vessel that is involved. Vasculitis may occur as a primary process or secondary to many systemic diseases. This topic provides an overview of the clinical features, diagnosis, and classification of the different forms of vasculitides.

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 Narrative Review of the Neurological Manifestations of Human Adenosine Deaminase 2 Deficiency

Deficiency of human adenosine deaminase type 2 (DADA2) is a complex systemic autoinflammatory disorder characterized by vasculopathy, immune dysregulation, and hematologic abnormalities. The most notable neurological manifestations of DADA2 are strokes that can manifest with various neurological symptoms and are potentially fatal. However, neurological presentations can be diverse. We here present a review of the neurological manifestations of DADA2 to increase clinical awareness of DADA2 as the underlying diagnosis. We reviewed all published cases of DADA2 from 1 January 2014 until 19 July 2022 found via PubMed. A total of 129 articles describing the clinical features of DADA2 were included in the analysis. Six hundred twenty-eight patients diagnosed with DADA2 were included in the review. 50.3% of patients had at least signs of one reported neurological event, which was the initial or sole manifestation in 5.7% and 0.6%, respectively. 77.5% of patients with neurological manifestations had at least signs of one cerebrovascular accident, with lacunar strokes being the most common and 35.9% of them having multiple stroke episodes. There is a remarkable predilection for the brain stem and deep gray matter, with 37.3% and 41.6% of ischemic strokes, respectively. Other neurological involvement included neuropathies, focal neurological deficits, ophthalmological findings, convulsions, and headaches. In summary, neurological manifestations affect a significant proportion of patients with DADA2, and the phenotype is broad. Neurological manifestations can be the first and single manifestation of DADA2. Therefore, stroke, encephalitis, posterior reversible encephalopathy syndrome, mononeuropathy and polyneuropathy, and Behçet's disease-like presentations should prompt the neurologist to exclude DADA2, especially but not only in childhood.

Deficiency of adenosine deaminase 2 (DADA2): Review

The deficiency of adenosine deaminase 2 (DADA2) is an autosomal recessive disease caused by loss-of-function (LOF) mutations in the ADA2 gene and was first described in 2014. Initially, it was described as vasculopathy/vasculitis that mostly affected infants and young children and closely resembled polyarteritis nodosa (PAN). Skin rash and ischemic/hemorrhagic stroke are predominant symptoms. However, the clinical spectrum of DADA2 has continued to expand since then. It has now been reported in adults as well. Besides vasculitis-related manifestations, hematological, immunological, and autoinflammatory manifestations are now well recognized. More than 100 disease-causing mutations have been described. The decrease in ADA2 enzyme leads to an increased extracellular adenosine level that, in turn, triggers a proinflammatory cascade. The disease is highly variable, and patients carrying same mutation may have different ages of presentation and clinical features. Anti-tumor necrosis factor (TNF) agents are mainstay of treatment of the vasculitis/vasculopathy phenotype. Hematopoietic stem cell transplant (HSCT) has been performed in patients with severe hematological manifestations. Recombinant ADA2 protein and gene therapy hold a promise for future.

A Cohort Study on Deficiency of ADA2 from China

PURPOSE

Deficiency of adenosine deaminase 2 (DADA2), an autosomal recessive autoinflammatory disorder caused by biallelic loss-of-function variants in adenosine deaminase 2 (ADA2), has not been systemically investigated in Chinese population yet. We aim to further characterize DADA2 cases in China.

METHODS

A retrospective analysis of patients with DADA2 identified through whole exome sequencing (WES) at seventeen rheumatology centers across China was conducted. Clinical characteristics, laboratory findings, genotype, and treatment response were analyzed.

RESULTS

Thirty patients with DADA2 were enrolled between January 2015 and December 2021. Adenosine deaminase 2 enzymatic activity was low in all tested cases to confirm pathogenicity. Median age of disease presentation was 4.3 years and the median age at diagnosis was 7.8 years. All but one patient presented during childhood and two subjects died from complications of their disease. The patients most commonly presented with systemic inflammation (92.9%), vasculitis (86.7%), and hypogammaglobinemia (73.3%) while one patient presented with bone marrow failure (BMF) with variable cytopenia. Twenty-three (76.7%) patients were treated with TNF inhibitors (TNFi), while two (6.7%) underwent hematopoietic stem cell transplantation (HSCT). They all achieved clinical remission. A total of thirty-nine ADA2 causative variants were identified, six of which were novel.

CONCLUSION

To establish early diagnosis and improve clinical outcomes, genetic screening and/or testing of ADA2 enzymatic activity should be performed in patients with suspected clinical features. TNFi is considered as first line treatment for those with vascular phenotypes. HSCT may be beneficial for those with hematological disease or in those who are refractory to TNFi.

Genotype and Phenotype of Adenosine Deaminase 2 Deficiency: a Report from Saudi Arabia

Adenosine deaminase 2 deficiency (DADA2), a rare and potentially fatal systemic autoinflammatory disease, is characterized by low or lack of ADA2 activity due to ADA2 mutations. DADA2 symptoms are variable and include vasculitis, immunodeficiency, and cytopenia. Minimal data are available from Saudi Arabia. This retrospective study conducted at seven major tertiary medical centers examined the phenotypic and genotypic variabilities, clinical and diagnostic findings, and treatment outcomes among 20 Saudi patients with DADA2 from 14 families. The median age of the study cohort was 9.5 years (4-26 years). The clinical presentation was before the age of 5 months in 25% of patients. Homozygous c.1447-1451del mutation was the most frequent ADA2 alteration (40%), followed by c.882-2A:G (30%). All tested patients exhibited absent or near-absent ADA2 activity. Phenotypic manifestations included stroke (40%), hematological abnormalities (95%), lymphoproliferation (65%), and recurrent infection (45%). Five and three patients had extracranial vasculitis features and Hodgkin lymphoma, respectively. Atypical manifestations included growth retardation (30%) and transverse myelitis. Anti-tumor necrosis factor (anti-TNF) therapy was the main treatment. Some patients underwent blood transfusion, splenectomy, cyclosporine and colony-stimulating factor therapies, and hematopoietic stem cell transplantation due to anti-TNF therapy failure. Fulminant hepatitis and septic multiorgan failure caused mortality in three patients. Thus, this study revealed the variability in the molecular and clinical characteristics of DADA2 in the study cohort with predominant aberrant hematological and immunological characteristics. Consensus diagnostic criteria will facilitate early diagnosis and treatment. Additionally, disease registries or large prospective studies are needed for evaluating rare disease complications, such as cancer.

Adenosine Deaminase 2 Deficiency Caused by Biallele Variants Including Splicing Variant: The First Case in Korea

Deficiency of adenosine deaminase 2 (DADA2) is an autoinflammatory disease caused by pathogenic variants of the ADA2 gene and has similar clinical features to polyarteritis nodosa (PAN). We, herein, report a case of DADA2 in Korea that was diagnosed in a patient with childhood-onset PAN. The patient had a truncal ataxia and facial palsy caused by thalamic infarction at 34 months of age. Livedo reticularis with Raynaud phenomenon and abdominal pain with fever were followed. Radiologic examination showed multiple infarctions in brain and kidney. She was diagnosed with PAN using skin biopsy and angiography. She had severe hemorrhagic strokes despite medical treatments. Her disease activity was controlled after adding a tumor necrosis factor-α inhibitor. Molecular analysis revealed compound heterozygous pathogenic variants of ADA2 gene. This is the first case of DADA2 in Korea. Genetic analysis for ADA2 gene should be considered in patients with childhood-onset PAN.

Polyarteritis nodosa

PURPOSE OF REVIEW

The aim is to review recent reports on childhood polyarteritis nodosa, including recent reports on treatment and outcome. Recently deficiency of adenosine deaminase-2 (ADA2), which may present as a polyarteritis nodosa-mimic, is becoming an important part of our practice. We also aim to highlight differences of childhood polyarteritis nodosa with deficiency of ADA2 as well as adult-onset disease.

RECENT FINDINGS

The few recent childhood series confirm the systemic nature of this vasculitis with predominantly medium-vessel involvement. American College of Rheumatology Vasculitis foundation has suggested recommendations for the management of this vasculitis. Unfortunately, we lack large patient numbers to provide us high evidence for the treatment of these patients. However, for induction mycophenolate mofetil or shorter courses of cyclophosphamide can be considered.Deficiency of ADA2 is now in the differential diagnosis of polyarteritis nodosa patients presenting with a family history and/or stroke with hematological and/or immunological abnormalities.

SUMMARY

We need collaborative work to define management and treatment strategies for childhood polyarteritis nodosa. Distinguishing deficiency of ADA2 is important because the treatment is different.

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.

Autoinflammation: Interferonopathies and Other Autoinflammatory Diseases

The family of autoinflammatory diseases (AIDs) continues to expand and now includes over 40 genetically defined disorders. Their defining feature is a dysregulated inflammatory innate immune response. Many AIDs have overlapping clinical characteristics, and dermatological manifestations are common. Autoinflammatory features have also been recognized in more common dermatological conditions such as psoriasis. Furthermore, there is an increasing understanding that immunodeficiencies, autoimmune disorders, and even some allergic disorders share overlapping autoinflammatory features. The discovery that certain somatic mutations, arising within the bone marrow and restricted to the myeloid cell lineage can cause acquired AID heralds a new era of discoveries in this field.

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.

The Many Faces of a Monogenic Autoinflammatory Disease: Adenosine Deaminase 2 Deficiency

PURPOSE OF REVIEW

We aim to describe the pathophysiology, clinical findings, diagnosis, and treatment of deficiency of adenosine deaminase 2 (DADA2).

RECENT FINDINGS

DADA2 is a multi-organ disease of children and less often adults, which can present with wide-ranging manifestations including strokes, medium vessel vasculitis, hematologic disease, and immunodeficiency. Diagnosis is through detection of reduced activity level of the adenosine deaminase 2 (ADA2) enzyme and/or identification of bi-allelic mutations in the ADA2 gene. Outside of high-dose glucocorticoids, conventional immunosuppression has been largely ineffective in treating this relapsing and remitting disease. Vasculitic-predominant manifestations respond extremely well to tumor necrosis factor-α inhibition. Hematopoietic stem cell transplantation can lead to normalization of enzyme activity, as well as resolution of vasculitic, hematologic, and immunologic manifestations, although treatment-related adverse effects are not uncommon. Early detection of this disease across multiple disciplines could prevent devastating clinical outcomes, especially in genetically pre-disposed populations.