Genetic targets in asthma

The purpose of this chapter is to review overall methodology and perspectives on the identification of potential genetic targets in allergy and asthma. Three examples of these approaches will be described in detail. Genetic studies have already led to advances in our understanding of basic disease processes, disease expression, and characterization of the asthmatic and allergic phenotypes (1,2). Multiple genes influence susceptibility to asthma, and disease expression is affected by these genetic factors. Complex genetic disorders are common in the population and are more prevalent than single-gene disorders, which are relatively rare (Table 1). Understanding the specific phenotype, as well as understanding relevant intermediate phenotypes, is important in dissecting the genetic components of these disorders (3). Genetic studies of allergy, bronchial hyperresponsiveness (BHR), and asthma require comprehensive scientific approaches since these conditions are characterized by heterogeneous phenotypic expression related to the complex interaction of environmental factors with multiple susceptibility genes. In addition, clinical disease, progression, and severity may be further influenced by different genes that influence disease expression as well as by viral respiratory infections, bacterial respiratory infections (endotoxin exposure), frequency of exposure to allergens, as well as other diverse environmental factors (4,5) (Fig. 1). Thus, delineating the role of genetic susceptibility in the expression and development of complex disorders and understanding the interaction between genes and the environment are of major public health significance.