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.