Editorial Commentary:Genetic Screening to Prevent Abacavir Hypersensitivity Reaction: Are We There Yet?

spective use of pharmacogenetic screening positively impacts patient outcome. Abacavir hypersensitivity reaction is a potentially life-threatening disease that occurs in ∼5% of patients initiating therapy with this drug. It sets itself apart from the majority of other drug toxicities encountered in clinical practice—which tend to be multifactorial in etiology, dose related, and pharmacologically predictable—in that its occurrence appears to be largely unrelated to dose, and its clinical presentation is more severe in cases of reexposure. Furthermore, clinical diagnosis of this disease (which most commonly presents 9‐11 days after initiation of therapy) has been confounded by an overlap of symptoms and signs with those of other drug hypersensitivities, viral infections, and immune restoration diseases. Although the occurrence of abacavir hypersensitivity reaction has been more common in Caucasian subjects (occurring in 8% of such subjects who initiate abacavir therapy), other clinical factors have not been useful in the prediction of this disease, and the risk of morbidity and even mortality on rechallenge precludes future use of abacavir in an individual who has been labeled with abacavir hypersensitivity syndrome.