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Clinical applications of pharmacogenetics in HIV

Mallal, S. (2008) Clinical applications of pharmacogenetics in HIV. In: Clinical Applications of Pharmacogenetics in HIV Symposium, 7 September 2008, Isla Verde, Puerto Rico.


Given on behalf of Dr. Elizabeth Phillips, Dr. Mallal presents pharmacogenetics and pharmacogenomics in clinical practice. Polymorphisms in both hosts and pathogens constitute a large challenge in therapy. Pathogenic adaptability, as seen in HIV, will shape the response to particular drug interventions. Similarly, the host genetic makeup will also affect the response to treatment. Drugs therefore help us elucidate these polymorphic backgrounds.

Pharmacogenetics refers to a clinical entity (phenotype) that is further characterized by genetics (genotype). Conversely, pharmacogenomics attempts to identify the genotype in order to predict the risk of developing a particular phenotype.

Pharmacogenetic and pharmacogenomic approaches in choosing an optimal antiretroviral regimen are exemplified in abacavir hypersensitivity reactions. Clinical diagnosis of abacavir hypersensitivity has been shown to yield false positives (CNA3005, CNA30024). This over diagnosis subsequently leads to prompt discontinuation of abacavir which incurs significant healthcare costs. A study by Dr. Phillips and colleagues (2005) demonstrated that disrupting treatment too early resulted in increased consultations with emergency physicians and/or specialists with higher costs for services. Furthermore, it took longer for these patients to achieve undetectable viral loads.

Studies show that abacavir hypersensitivity can be more accurately diagnosed with the patch test. Dr. Mallal reiterates the differences between pharmacogenetics and pharmacogenomics by pointing out that patch testing should be employed in abacavir sensitized individuals, therefore serving as a diagnostic test and not a predictive test.

Publication Type: Conference Item
Murdoch Affiliation: Centre for Clinical Immunology and Biomedical Statistics
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