How is it used?
Genotypic resistance testing helps doctors make better treatment decisions for their patients when existing anti-viral therapies are not working effectively. If drug resistance is found, a new treatment regimen may be chosen.
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When is it requested?
Genotypic resistance testing is requested on first diagnosis, when starting antiretroviral therapy, and when
viral load values (a measure of how much
HIV is in your body) rise steadily during therapy, indicating treatment failure and the possibility of resistance.
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What does the test result mean?
The test result identifies the viral
mutations. These are described by a combination of letters and numbers, for example K103N. Based on the test result, your doctor will identify whether a given mutation is one known to cause drug resistance. Not all mutations cause drug resistance.
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Is there anything else I should know?
Genotypic resistance testing is used by specialist doctors who treat patients with
HIV and is not available everywhere.
The test is not good at detecting 'minority' mutations, which affect less than 20% of the virus population.
Genotypic resistance testing works best on blood samples with a viral load of at least 1,000 copies per millilitre of blood. If your viral load is very low, the test probably won’t work.
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