Observational Safety Study for KALBITOR (Ecallantide) in the Treatment of Acute Attacks of Hereditary Angioedema

The objective of this study is to evaluate immunogenicity and hypersensitivity upon exposure
to KALBITOR, in particular:

1. Determine the rate of anaphylaxis and Type I hypersensitivity reactions upon exposure to
KALBITOR.

2. Determine the rate of seroconversion to anti-ecallantide antibodies upon exposure to
KALBITOR.

3. Determine the rate of adverse events related to disordered coagulation
(hypercoagulability and hypocoagulability) upon exposure to KALBITOR.

Inclusion Criteria:

- Patients indicated per the approved product label for KALBITOR

- Patient or guardian is able to understand and sign the informed consent form

- Patient is willing and able to undergo a skin test procedure at screening (baseline)

Exclusion Criteria:

- Patient contraindicated per the approved product label for KALBITOR

- Patient confirmed pregnancy or active breastfeeding

- Any other condition that, in the opinion of the Investigator, may compromise the
safety or compliance of the patient or would preclude the patient from successful
completion of the study