Background and purpose: Asthma is a chronic inflammatory disease of the airways that is caused by hypersensitivity to environmental allergens. Symptoms of asthma include shortness of breath, airway hyper-responsiveness, wheezing, and cough. The disease might vary from a mild to severe and intermittent to chronic disease. Asthma is known as a multifactorial disease due to the interaction of genetic and environmental factors in its development. Identifying the environmental and genetic factors are of great benefit for prevention, diagnosis and treatment of allergic asthma. The aim of this review was to investigate the factors that increase the risk of asthma.
Materials and methods: Electronic databases including Scopus, PubMed, Google Scholar, Scientific Information Database (SID), Magiran, and Irandoc were searched for relevant articles published between 1990 and 2016. The search keywords were asthma, atopy, genetic factors, polymorphisms, environmental factors, and gene-environment interaction.
Results: This review showed that asthma is a complex and multifactorial disease and the combination and interaction of environmental and genetic factors have a role in its development and progression. Therefore, each of these factors cannot be considered as an absolute cause of asthma, but a set of factors such as genes influencing inflammatory pathways, airway rebuilding, and environmental factors should be considered as risk factors.
Conclusion: Asthma is a complex and multifactorial disease and interaction of several genetic and environmental factors are involved in its clinical presentation. A major step in determining the genetic causes of asthma is identifying chromosomal regions and candidate genes associated with asthma.