Asthma phenotypes.
OBJECTIVE
Asthma is a heterogeneous disorder presenting with many phenotypes. Precise phenotypic definition has eluded the medical research community for years, despite recognition of different disease subtypes. Improved phenotypic characterization and knowledge of underlying pathobiology is necessary for linkage of specific genotypes with clinical disease manifestations.


RESULTS
Phenotyping has been difficult because asthma is likely to be comprised of overlapping syndromes with varying origins and heterogeneous pathobiology. Currently, the field is too reliant on classification by trigger or symptoms. Since genotypic and phenotypic heterogeneity are inherent in asthma, patients presenting with different asthma phenotypes may need tailored therapies. Studies have begun to link genetics with disease mechanism and therapeutic response. As disease etiology, onset, progression and severity vary greatly among patients, however, the relative contribution of genetic factors may be difficult to ascertain. Definition of the full array of complex biological consequences of molecular target modulation is a prerequisite for therapies based on this concept.


CONCLUSIONS
The advent of targeted therapies for asthma and clinical trials based on phenotype and genotype have raised interest in more accurate description of asthma phenotypes. Therapies based on phenotypic and genotypic characteristics may be useful in asthma management. A variety of factors, however, must be addressed before such approaches become standard.
Kiley
James
J
Division of Lung Diseases, National Heart, Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-7952, USA. kileyj@nhlbi.nih.gov
Smith
Robert
R
Noel
Patricia
P
D001241:Aspirin / Q000009:adverse effects; D001249:Asthma / Q000209:etiology* / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005938:Glucocorticoids / Q000009:adverse effects; D006801:Humans; D006967:Hypersensitivity / Q000150:complications; D010641:Phenotype; D012123:Pulmonary Ventilation / Q000502:physiology
D005938:Glucocorticoids; D001241:Aspirin