Atopy

Atopy is a genetic predisposition to develop IgE-mediated responses to common environmental allergens, leading to a higher likelihood of allergic diseases such as atopic dermatitis, allergic rhinitis, asthma, and food allergy. It is not a single disease but a tendency that can manifest in different organs and at different life stages. A family history of atopy and elevated levels of IgE are commonly observed in affected individuals.

The pathophysiology of atopy involves a combination of genetic susceptibility and environmental exposure. Variants in skin barrier genes, such as filaggrin, can increase skin permeability and promote sensitization, particularly in atopic dermatitis. The immune response is often skewed toward a T helper 2 (Th2) profile, with production of allergen-specific IgE antibodies. Recurrent exposure to environmental allergens can lead to ongoing symptoms across multiple organ systems.

Common clinical manifestations include atopic dermatitis (pruritic, chronic eczema often in flexural areas), allergic rhinitis (nasal itching, sneezing, congestion), and asthma (episodic wheeze and shortness of breath). Food allergies can cause immediate reactions to specific foods. The presentation can vary with age and individual risk factors.

Diagnosis is based on history and examination, supported by allergy testing when appropriate. Skin prick testing or serum-specific IgE testing can identify sensitization to particular allergens; total IgE levels alone are not diagnostic. Oral food challenges may be used in some cases.

Management focuses on avoidance of known triggers and control of symptoms. Emollients and barrier repair are central to atopic dermatitis, with topical corticosteroids or calcineurin inhibitors for inflammation. Allergic rhinitis and asthma are treated with guideline-based pharmacotherapy; allergen immunotherapy may help select patients. Prognosis varies; many children experience improvement with age, while others require lifelong management due to persistent atopy and comorbid conditions.