Considerable progress has been made in the field of molecular biology in recent years, enabling the study of sensitization to the individual components of an allergenic source, a practice that has been termed molecular allergy diagnosis (MD) or component-resolved diagnosis (CRD).
The present review provides the clinician with a practical approach to the use of MD by answering questions frequently asked by physicians on how MD can help improve the diagnosis of allergy in daily clinical practice.
The article is divided into 3 sections. First, we provide a brief review of the importance for the clinician of knowing the main allergens in the different allergenic sources, their structure, and their in vitro cross-reactivity before approaching MD (section A). Second, we review the usefulness of MD in clinical practice (section B) and answer frequently asked questions on the subject. Finally, section C addresses the interpretation of MD and its integration with other tools available for the diagnosis of allergy.

Key words: Molecular allergy diagnosis (MD), Component-resolved diagnosis (CRD), Allergen component, Genuine sensitization, Cross-reactivity