When designing an experiment, every scientist knows that it’s important to control for as many potentially confounding variables as possible.
Suppose you want to test the effects of a drug in a mouse model. In this case, you want to make sure that animals in the control groups receive equivalent treatment as animals in the test groups. For instance, if you deliver the drug by injection, then an equivalent saline injection should be administered to the control group. A carefully designed experiment allows you to pick up the subtle effects of your drug treatment.
But what if some variables are out of your control? A soon-to-be published article in Nature Genetics suggests that common laboratory mouse strains contain significant genetic variability. The authors performed a comprehensive analysis of mice at Jackson Laboratories, a major scientific supplier.
Genotype is a powerful modulator of drug response. For instance, one variant of a gene might code for an enzyme that metabolizes drug at a faster rate than the wild type enzyme. Unfortunately, this means that our hypothetical experiment could be confounded by uncontrolled genetic variability.
Coincidentally, this year happens to be the 50th anniversary of the field of pharmacogenetics (this is the first review). When the price of human genotyping drops sufficiently, this field could revolutionize the way doctors prescribe medicine. However, this kind of personalized medicine depends on basic research. For this research to mean anything, we need to be confident about the genotypes of our animal models.
Science Daily provides a nice summary of the research findings.