Validation of Laser Doppler Flowmetry to Identify Allergic Rhinitis Patients With Pharmacogenetic Alterations in Histamine Metabolism

The specific aim of this study is to validate iontophoresis (with measurement of
microvascular blood flow by laser Doppler flowmetry) in a pediatric cohort as a surrogate
marker capable of reliably characterizing the normal physiologic response of the cutaneous
microvasculature to histamine. In future studies laser Doppler flowmetry ultimately will be
used to assess whether microvascular blood flow determined by a previously validated laser
Doppler technique can be used as a reliable surrogate endpoint capable of functionally
discriminating the effects of polymorphisms in the genes which are quantitatively important
for histamine metabolism. The hypothesis to be proven is that histamine iontophoresis with
measurement of microvascular blood flow by laser Doppler flowmetry can be used as a reliable
marker to characterize the normal microvascular cutaneous response to histamine.

Inclusion Criteria:

diagnosed with allergic rhinitis by an attending Pediatrician or Allergist (diagnosis made
on clinical grounds or by positive skin test or RAST to environmental allergens, trees,
grass, weeds, mold, animal dander, cockroach, dust mite)

Exclusion Criteria:

history or evidence of McCune Albright syndrome, immunodeficiency, mastocytosis, receipt
of allergy shots, chronic skin disease, liver or kidney disease, cancer, neurological
movement disorders, uncontrolled ADHD, evidence of eczema currently or in the past 2
years, history of anaphylaxis or anaphylactic like episode, evidence of pregnancy (by
urinary hCG) or lactation, use of antihistamines 10 days prior to skin testing, use of
systemic corticosteroids or tricyclic antidepressants 30 days prior to skin testing,
presence of condition that would cause difficulty in adherence with study procedure.