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

Hematopoietic stem cell transplantation rescues the hematological, immunological, and vascular phenotype in DADA2

Deficiency of adenosine deaminase 2 (DADA2) is caused by biallelic deleterious mutations in CECR1 DADA2 results in variable autoinflammation and vasculopathy (recurrent fevers, livedo reticularis, polyarteritis nodosa, lacunar ischemic strokes, and intracranial hemorrhages), immunodeficiency and bone marrow failure. Tumor necrosis factor-α blockade is the treatment of choice for the autoinflammation and vascular manifestations. Hematopoietic stem cell transplantation (HSCT) represents a potential definitive treatment. We present a cohort of 14 patients from 6 countries who received HSCT for DADA2. Indication for HSCT was bone marrow dysfunction or immunodeficiency. Six of 14 patients had vasculitis pre-HSCT. The median age at HSCT was 7.5 years. Conditioning regimens were myeloablative (9) and reduced intensity (5). Donors were HLA-matched sibling (n = 1), HLA-matched unrelated (n = 9), HLA-mismatched unrelated (n = 3), and HLA haploidentical sibling (n = 1). All patients are alive and well with no new vascular events and resolution of hematological and immunological phenotype at a median follow-up of 18 months (range, 5 months to 13 years). Plasma ADA2 enzyme activity normalized in those tested post-HSCT (7/7), as early as day +14 (myeloid engraftment). Post-HSCT hematological autoimmunity (cytopenias) was reported in 4 patients, acute graft-versus-host disease grade 1 in 2, grade 2 in 3, and grade 3-4 in 1, and moderate chronic graft-versus-host disease in 1 patient. In conclusion, in 14 patients, HSCT was an effective and definitive treatment of DADA2.

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.

Clinical, imaging and genotypical features of three deceased and five surviving cases with ADA2 deficiency

Deficiency of adenosine deaminase type 2 (DADA2) is a rare form of autoinflammatory disorder with limited reported cases. In this paper, we have presented the clinico-immunological, radiological and genetic characteristics of five surviving and three deceased childhood-onset DADA2 patients. We aimed to compare surviving and deceased patients in terms of clinical features and treatment modalities. Moreover, we have evaluated the causes of death in our DADA2 subjects together with the previously reported cases. Demographic features, clinical characteristics, imaging findings, mutations and pharmacological treatments of DADA2 subjects were noted from patient records of pediatric and adult rheumatology clinics in a retrospective and longitudinal nature. Eight patients from seven families were enrolled. While five of them were surviving, three of them had died due to various reasons. Median age of the patients at disease onset and diagnosis was 7 years (range 0.5-13 years) and 14 years (range 5-27 years), respectively. The main clinical manifestations were cutaneous findings (7/8), recurrent low-grade fever (6/8), neurological involvement (6/8) and gastrointestinal involvement (5/8). All patients had increased acute phase reactants at presentation and also during the disease flares. Until the diagnosis of DADA2 was confirmed, five patients have been followed-up with the diagnosis of PAN: two patients both with PAN and FMF, and one patient with CAPS and vasculitis. Demographic, clinical, neurological features and genetic mutations did not differ in surviving and deceased DADA2 patients. Deceased and surviving subjects differed in terms of treatment modalities after the diagnosis of DADA2. Anti-TNF alpha treatment has been initiated in five surviving patients as soon as the diagnosis of DADA2 was established. However, three patients who have died were not able to use sufficient doses of anti-TNF alpha treatment; in one case due to reluctance of patient and in two cases due to establishment of the definite diagnosis by genetic analysis at the same time with the last fatal DADA2 episode. Despite limited number of patients, this case series for the first time compares the phenotypic, genotypic and medication differences between surviving and deceased DADA2 patients. Anti-TNF alpha treatment seems to be efficient and lifesaving in DADA2 patients.