Deficiency of adenosine deaminase 2 as an unrecognized cause of early-onset stroke and cranial nerve palsy

OBJECTIVE: The aim of this study is to evaluate the clinical, laboratory, and radiological findings and prognosis of patients with adenosine deaminase 2 deficiency (DADA2) and to highlight the conditions that DADA2 should be considered in the differential diagnosis in patients with neurological findings. METHODS: A case series of six DADA2 patients was presented in this retrospective, descriptive study. Clinical and laboratory data, treatment protocols, and prognosis of the patients were recorded. A diagnosis of DADA2 was established by ADA2 enzyme activity assay and/or ADA2 gene sequencing. RESULTS: Six patients with DADA2 were included in the study. The median age at symptom onset was 6.5 years (range 3.5–13.5 years). The median time to diagnosis from the initial presentation was 9 (3–72) months. Consanguinity was present in the families of 4 cases. The skin, nervous system, and musculoskeletal system were the most commonly involved systems. Vasculitis mimicking polyarteritis nodosa (PAN) was the predominant phenotype (n=4) in our case series. Four patients with PAN-like features had neurological involvement. Ischemic strokes were found in 3 patients, cranial nerve palsy in 2 patients, and seizures in 2 patients. The CECR1 gene was analyzed in all patients. We analyzed plasma ADA2 enzyme activity only in one patient. Anti-tumor necrosis factor (TNF)-α therapy was initiated. Inflammation was suppressed and remission was achieved in all patients. CONCLUSION: DADA2 should be considered in patients with PAN-like disease, a history of familial PAN/vasculitis, early-onset strokes/neurological involvement with systemic inflammation. Furthermore, anti-TNF-α therapy appears to be beneficial for the treatment of DADA2.