A Prospective, Non-interventional, Observational Study of Presentation, Treatment Patterns and Outcomes in Atypical Hemolytic Uremic Syndrome Patients

Inclusion Criteria: Participants are eligible to be included in the study. Age 1. Patients of any age, who are diagnosed as aHUS by a professional physician (first epi-sode or relapse). Type of Patient and Disease Characteristics 2. Evidence of TMA, including thrombocytopenia, evidence of hemolysis, and kidney dys-function, based on the following laboratory findings, should be recorded within 2 weeks time frame: 1. Platelet count \< 150,000 per microliter (μL), and 2. Mechanic hemolytic anemia evident by LDH ≥ 1.5 × upper limit of normal (ULN), and hemoglobin ≤ lower limit of normal (LLN) for age and gender and 3. Serum creatinine level ≥ ULN in adults (≥18 years of age), or ≥ 97.5th percentile for age at screening in children (patients who require dialysis for acute kidney injury are also eligi-ble). 3. Gender: Male and/or female. Informed Consent 4. Willing and able to give written informed consent and comply with the study visit schedule as described in Section 6.2.1. For patients \< 18 years of age, patient's legal guardian must be willing and able to give written informed consent and the patient must be willing to give written informed assent (if applicable as determined by the central. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: Medical Conditions 1. Patients who were diagnosed with HUS only due to Shiga toxin-producing Escherichia coli (STEC). 2. Patients who were diagnosed with TTP (ADAMTS13 activity \<10%). Other Exclusions 3. Unable to give written informed consent. 4. Any medical or psychological condition that, in the opinion of the Investigator, could increase the risk to the participant by participating in the study or confound the outcome of the study.