Genetics of asthma and allergy: what have we learned?

The overall purpose of this review is to present an update on genetic approaches to understanding the susceptibility and expression (severity) of common diseases, such as asthma and allergy. Five key questions are addressed in this review: (1) What phenotypes are being studied? Multiple disease phenotypes in carefully characterized patients are required. (2) Are the same genes that are important in disease susceptibility important in disease severity? (3) Are there racial differences in disease expression and genetic susceptibility? (4) Are the genes important in normal variation in lung function important in asthma severity? (5) Are the genes important in other common diseases, such as chronic inflammatory diseases or chronic obstructive pulmonary disease, important in asthma or allergy? In addition, a discussion of some of current areas of research is presented, including the issue that current genome-wide association study results do not account for a significant portion of trait variability, the potential role of rare variants and large genome-sequencing studies, and pharmacogenetics: is there a role for basing treatment decisions on the results of genetic testing? Finally, the potential usefulness of DNA, personalized medicine, is discussed.