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Background: Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy (TMA), which has been treated successfully with eculizumab. The optimal duration of eculizumab in treating patients with aHUS remains poorly defined. Methods: We conducted a multicenter retrospective study in the Arabian Gulf region for children of less than 18 years of age who were diagnosed with aHUS and who discontinued eculizumab between June 2013 and June 2021 to assess the rate and risk factors of aHUS recurrence. Results: We analyzed 28 patients with a clinical diagnosis of aHUS who had discontinued eculizumab. The most common reason for the discontinuation of eculizumab was renal and hematological remission (71.4%), followed by negative genetic testing (28.6%). During a median follow-up period of 24 months after discontinuation, 8 patients (28.5%) experienced HUS relapse. The risk factors of recurrence were positive genetic mutations (p = 0.020). On the other hand, there was no significant relationship between the relapse and age of presentation, the need for acute dialysis, the duration of eculizumab therapy before discontinuation, or the timing of eculizumab after the presentation. Regarding the renal outcomes after discontinuation, 23 patients were in remission with normal renal function, while 4 patients had chronic kidney disease (CKD) (three of them had pre-existing chronic kidney disease (CKD) before discontinuation, and one case developed a new CKD after discontinuation) and one patient underwent transplantation. Conclusions: The discontinuation of eculizumab in patients with aHUS is not without risk; it can result in HUS recurrence. Eculizumab discontinuation can be performed with close monitoring of the patients. It is essential to assess risk the factors for relapse before eculizumab discontinuation, in particular in children with a positive complement variant and any degree of residual CKD, as HUS relapse may lead to additional loss of kidney function. Resuming eculizumab promptly after relapse is effective in most patients.

Importance: Hypermanganesemia with dystonia type 2 is a rare autosomal recessive neurodegenerative disorder characterized by the loss of previously acquired milestones, dystonia, parkinsonian features, a high serum manganese level, and characteristic neuroimaging findings such as bilateral and symmetrically increased T1 and decreased T2/fluid-attenuated inversion recovery signal intensity in the basal ganglia. This condition is secondary to a mutation in the SLC39A14 gene. Objective: To present a series of three cases of hypermanganesemia with dystonia type 2, which was genetically confirmed secondary to a mutation in the SLC39A14 gene, and to describe the treatment and clinical course in these cases. Design: A retrospective case series. Setting: University, Tertiary hospital. Participants: Three unrelated pediatric patients with hypermanganesemia with dystonia type 2, genetically confirmed to be secondary to a mutation in the SLC39A14 gene. Exposures: Chelation therapy using calcium disodium edetate. Main outcome(s) and measure(s): The response to chelation therapy based on clinical improvements in motor and cognition developments. Results: All three patients were started on chelation therapy using calcium disodium edetate, and two of them showed an improvement in their clinical course. The chelation therapy could alter the course of the disease and prevent deterioration in the clinical setting. Conclusions and Relevance: Early diagnosis and intervention with chelating agents, such as calcium disodium edetate, will help change the outcome in patients with hypermanganesemia with dystonia type 2. This finding highlights the importance of early diagnosis and treatment in improving the outcomes of patients with treatable neurodegenerative disorders.