Deconstructing the Atopic March - the Role of Filaggrin Mutations and Sensitization Pathways in Allergic Rhinitis and Peanut Allergy

Participants with confirmed history of birch induced allergic rhinitis or peanut allergy or that are non-atopic will undergo the following procedures.

If not already completed in the previous year, participants will be skin tested to a panel of common environmental allergens, including birch pollen and peanut. To be considered "non-atopic", all skin tests in the panel must be negative in the presence of a positive histamine control. All participants will also be skin tested to peanut, Arah 2, Ara h 8 (if obtainable), crushed raw unroasted peanut, peanut butter, peanut extract, Bet v 1 and birch pollen extract.

Blood samples will be drawn for genotyping of the four most common null mutations in FLG in Caucasians (R501X, 2282del4, R2447X, S3247X).

Patch testing will be performed using Ara h2, Arah8 (if obtainable), crushed raw unroasted peanut, peanut butter, peanut extract, Bet v 1 and birch pollen extract. Peanut and birch pollen allergens, both whole and components will be diluted 1:10 in both saline and petroleum jelly and applied to normal controls skin to establish levels for irritant reaction. If further dilutions are required to show non-irritation these will be performed.

As well, a limited medical history and medication history will be documented, with a focus on atopic disorders (i.e. atopic dermatitis (eczema), allergic rhinitis, asthma, and food allergy). Those in the non-allergic control group will be excluded if they have features of eczema, food allergy or other atopic conditions). Medications that could potentially interfere with the skin test results (i.e. antihistamines) must be documented, and appropriate washout intervals observed prior to the skin test procedure, if necessary.