Post-marketing safety data on patients treated and untreated with eculizumab or ravulizumab.

The study will capture post-marketing safety data on patients treated with eculizumab or ravulizumab. Additionally, the study will collect information on the progression of disease in all patients.

Inclusion Criteria:

• Male or female patients of any age, including minors, who have been diagnosed with aHUS
• Patients with or without an identified complement pathogenic variant or anti-complement factor antibody
• Able to give written informed consent. Patient or patient's parent/legal guardian must be willing and able to given written informed consent and the patient (if minor) must be willing to give written informed assent [if applicable as determined by the central Institutional Review Boards/Independent Ethics Committees (IRB/IEC)].
• ADAMTS13 > 5%, if performed.

Exclusion Criteria:

• Hemolytic Uremic Syndrome (HUS) only due to Shiga Toxin producing Escherichia coli (STEC).
• Unable to give written informed consent. Patient or patient's parent/legal guardian unable to give written informed consent. Patient (if minor) unable to give written informed assent (if applicable as determined by the central Institutional Review Boards/Independent Ethics Committees [IRB/IEC]).

Male or female patients of any age, including minors, who have been diagnosed with aHUS; clinical diagnosis of aHUS, patients with or without an identified complement regulatory factor genetic abnormality or anti-complement factor antibody, ADAMTS13 > 5% (if performed)