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genotyping vs. phenotyping
Jun 26, 2000

After 4+ years of undetectable viral load my VL has suddenly become detectable at the 4000 level. Current meds are Indinavir, Combivir. CD4+ is in 800-1000 range with IL-2. I am being retested -- VL, CD4* prior to changing meds. At the same time my doctor is doing resistance tests. I have been reading about genotyping and phenotyping. What exactly is the difference and do you think one is superior to the other in determining what medicines to move to? Thank you for having this forum which always is informative and usually encourages me.

Response from Dr. Holodniy

That is the million dollar question. We do not know yet whether one test is "better" than the other. When I say this, I mean whether one test is more accurate or predictive of current drug failure or future drug response. These studies are ongoing. In general, the information provided from each kind of test, correlates with the other. With a viral load like yours, there is a high likelihood of resistance to one or more of the meds in your regimen. Given your regimen, there will be resistance to 3TC from combivir. There may not be indinavir resistance based on some of data from published studies. Therefore, you may not have to abandon the whole regimen.


infectious disease vs. hiv specialist ??
Is it too late?

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