Defining the allergen sensitization of a patient with asthma at the molecular level by measuring specific IgE to purified natural or recombinant allergens can improve diagnostic accuracy and improve asthma phenotyping.

Molecular diagnosis is possible thanks to the specificity of some markers of species-specific sensitization and resolve cross-reactivity phenomena from a true co-sensitization. None of this precision is possible with conventional allergy tests, and such information will eventually give clinicians the possibility to individualize the actions taken, including indications on reducing targeted-allergen exposure or selection of suitable allergens for specific immunotherapy, thereby increasing the safety and efficacy of immunotherapy. Nevertheless, all in vitro tests should be assessed alongside clinical history, as allergen sensitization does not necessarily imply clinical responsiveness.