Asthma, and severe asthma, in particular, is a heterogeneous disease.
Traditional views of asthma have centered around a childhood onset disease with an allergic component. However, severe asthma can present in multiple different ways, and only 30-50% meet traditional childhood onset allergic criteria.
Severe asthma - differential diagnosis and management (click to enlarge the image).
A phenotype is clinical characteristics that are the product of the interaction of the patient's genes with the environment.
There are 3-5 common clinical phenotypes of severe asthma in adults:
- early onset severe allergic asthma
- late onset non-atopic eosinophilic asthma
- late onset non-eosinophilic asthma with obesity
However, there is a big problem with the phenotypes - they do not identify a target population for a specific therapy.
As biological characteristics are better identified (cell markers, interleukins, etc.), phenotypes could evolve into asthma endotypes.
Endotypes could be identified based on matching:
- biology (cell types, interleukins)
- therapeutic responses
This integration of genetics, biology and clinical characteristics can enabled us to effectively treat complex heterogeneous diseases, such as severe asthma.
Current treatment of severe asthma. Hashimoto S, Bel EH. Clin Exp Allergy. 2011 Dec 12. doi: 10.1111/j.1365-2222.2011.03936.x.