To the Editor The study by Dr Chung and colleagues1 identified CYP2C variants, which participate in drug clearance,2 as important genetic factors associated with phenytoin-related severe cutaneous adverse reactions. Nevertheless, their analysis did not take into account the potential influence of coadministered drugs. For this reason, I would like to comment on the importance of drug interactions in pharmacogenetic studies, which are designed to examine the influence of certain genetic variants on drug pharmacokinetics (eg, pharmacological and/or toxic dose-dependent activity).
Lozano R. Genetic Factors Associated With Severe Cutaneous Adverse Reactions. JAMA. 2014;312(20):2165-2166. doi:10.1001/jama.2014.14145