Cause of Unexplained Anaphylaxis

• INCLUSION CRITERIA:

Subject must be at least 13 years of age and no older than 70 years of age.

Diagnosis of anaphylaxis occuring in the absence of an identitiable provoking agent of stimulus (Idiopathic Anaphylaxis [IA]) by a referral physician. Patient may carry both the diagnosis of 1A and the diagnosisi of anaphylaxis provoked by an identified stimulus.

History of anaphylaxis with a minimum of 3 episodes in the past year.

One doctor's office or ER visit of hospitalization on for anaphylaxis without an established etiology with involvement of the skin and/or mucosal tissue (e.g., flushing, itching, hives, angioedema, tongue swelling) and at least on the the following:

• Elevated serum tryptase above subject's baseline measurement within 6 hours of the event.
• Respiratory compromise (e.g., dyspnea, hoarseness-laryngeal edema, wheeze-bronchospasm, stridor, reduced peak expiratory flow, hypoxemia).
• Gastrointestinal symptoms of vomiting and/or diarrhea
• Reduced blood pressure and/or associated symptoms of end-organ dysfunction (as evidenced hypotonia, hypoxia, collapse, syncope or incontinence).

Letter of referral from prospective study participant's referring physician, with copies of available medical evaluation and laboratory studies

Able and willing to consider a bone marrow biopsy and aspirate

EXCLUSION CRITERIA:

Presence of conditions which in the judgment of the investigator or the referring physician may put the subject at undue risk for travel (including frequent episodes of IA not preventable by pre-medication, acute infection, severe thrombocytopenia [minimum platelet count of 30,000], or significant cardiovascular disease)

Any medical condition that in the view of the principal investigator would make the subject unsuitable for enrollment in this study (such as advanced renal disease).

Inability to provide informed consent