Patient description: The patient is a 15 year old girl with the history of recurrent bilateral headache. The attacks come 2 times or more per week and each episode lasts around a day or a half. The pain is pulsating in quality and severe in intensity, causing trouble in her routine physical activity. The attacks are associated with nausea and photophobia. She recently noticed that that there are more attacks around her menstrual period. She is diagnosed with the migraine headache and is under treatment. She is a high-school student and living with her both parents. She is a book worm and spend her free time in a public library near her home. She is also interested in writing stories and has several short stories in English. She rarely does exercise. Her BMI is 21 with the BP of 100/60. There is nothing remarkable in her physical exam.

Clinical trial eligibility criteria: eligible ages (years): 12.0-999.0,  Angioedema The Participant will not be considered eligible for the study without meeting all of the applicable population below Males and females, 12 years of age and older for participants with non-histaminergic normal C1-INH angioedema at the time of signing of the informed consent form (ICF) Documented clinical history of recurrent attacks of angioedema in the absence of wheals/urticaria Investigator-confirmed diagnosis of non-histaminergic bradykinin-mediated angioedema with normal C1-INH as documented by a history of angioedema attack(s) at screening and occurrence of attacks during the observation period History of recurrent angioedema with at least an average of 1 angioedema attack per 4 weeks prior to screening and this attack rate must be confirmed during the observation period while treated with chronic high-dose antihistamine (cetirizine 40 milligram per day [mg/day] or equivalent high-dose second-generation antihistamine medication) Diagnostic testing results obtained during screening from a sponsor-approved central laboratory that confirm C1-INH function greater than or equal to (>=) 50 percent (%) of normal and normal C4. With prior sponsor approval, participants may be retested during the observation period if results are incongruent with clinical history Clinical history of not responding to high-dose antihistamine treatment (cetirizine 40 mg/day or equivalent high-dose second-generation antihistamine medication), which must be confirmed during the observation period with at least 1 angioedema attack per 4 weeks with chronic high-dose antihistamine treatment and no significant difference (as assessed by the investigator and in consultation with the sponsor's medical monitor, as necessary) from the historic attack rate without high-dose antihistamine treatment Agree to adhere to the protocol-defined schedule of treatments, assessments, and procedures Participants >= 18 years of age must be willing to use icatibant as the rescue medication during the observation and treatment period. During the observation period, participants need to be treated with icatibant for at least 2 angioedema attacks or at least 1 moderate or severe attack. In the opinion of the investigator, participants with no response to icatibant for acute angioedema attacks in the past medical history/screening, or no improvement or worsened attack severity 2 hours after icatibant treatment during the observation period (based on totality of assessments), will not be included. Note: For participants 12 to less than (<) 18 years of age, standard of care therapy per local protocols should be provided Males, or non-pregnant, non-lactating females who are of child-bearing potential and who agree to be abstinent or agree to comply with the applicable contraceptive requirements of this protocol for the duration of the study. Female participants of childbearing potential must have a negative serum pregnancy test at screening and must be willing to undergo pregnancy tests throughout the study. Females of non-childbearing potential are defined as surgically sterile (status post hysterectomy, bilateral oophorectomy, or bilateral tubal ligation) or post-menopausal for at least 12 months  The participant will be excluded from the study if any of the following are met Concomitant diagnosis of Type I or Type II HAE, or recurrent angioedema associated with urticaria Dosing with any investigational drug or exposure to an investigational device within 4 weeks prior to screening Exposure to angiotensin-converting enzyme (ACE) inhibitors or rituximab within 6 months prior to screening Use of any estrogen-containing medications with systemic absorption (such as oral contraceptives or hormonal replacement therapy) within 4 weeks prior to screening Response to omalizumab (prophylactic) or corticosteroid (acute/prophylactic) or epinephrine (acute) or anti-leukotrienes (prophylactic) treatments in the past Use of long-term prophylactic therapy for HAE, e.g. C1-INH, attenuated androgens (e.g. danazol, methyltestosterone, testosterone), or anti-fibrinolytics within 2 weeks prior to entering the observation period as long as the investigator determines that doing so would not place the participant at any undue safety risk, and that the participant is at least 18 years of age Any exposure to prophylactic plasma kallikrein inhibitors prior to screening Use of short-term prophylaxis for HAE within 7 days prior to entering the observation period. Short-term prophylaxis is defined as C1-INH, attenuated androgens, or anti-fibrinolytics used to avoid angioedema complications from medically indicated procedures