The National Center for Biotechnology Information determined that in 1994 there were over 2.2 million cases of adverse drug reactions in the U.S. Adverse drug reactions, which are rooted in individuals’ variable responses to medication, are a major cause of hospitalizations. Medications and doses, which are developed around the average response of a population, may affect each individual very differently.
Pharmacogenomics refers to the study of the numerous genes in an individual that determine his or her reaction to drugs. Each drug acts on a particular metabolic pathway in the human body. Each pathway involves many proteins, and therefore many genes.
A person’s genetic make up can have a profound influence on how he or she will respond to a drug. This discovery has led to the study of pharmacogenetics, which refers to the relationship between an individual’s genetic profile and his or her corresponding drug metabolism and response. Genetic tests, which analyze an individual’s genomic pattern of SNPs, can reliably predict his or her likely response to a given drug. The successful pharmacogenetic analysis of an individual will, ideally, lead to a doctor prescribing the best drug at a dose that will maximize the benefits while minimizing the risk.
Genetic testing facilities currently use several methods of genotyping, from traditional DNA sequencing to mass spectrometry to microarray technology. The first bottleneck of pharmacogenetics, however, is sample collection and DNA preparation.
The dominant method of sample collection involves the use of traditional vacutainer-based blood samples, which has a number of drawbacks. First, individuals participating in a study or drug trial must have their blood drawn by skilled personnel at a centralized location, and the drawn samples necessitate refrigeration. Shipping the blood, which is designated as a biohazardous material, requires ice and insulated packaging.
Extracting DNA from the blood samples, a task performed at a genotyping laboratory, requires labor-intensive and time-consuming methods. Finally, the extracted DNA samples must be stored in -70C freezers, which are both expensive and susceptible to electrical power outages. A common technique used to mitigate this risk involves storing portions of each sample in several locations, thus requiring redundant freezer units, labor, and electricity.