Dear Dr. Mark,

I recently sent you a question about the lab's inability to phenosense test my virus. You were unable to answer my question and said you would like to know exactly what the response from the lab message was, so here goes:

Phenosense could not be completed on this sample due to an atypical genetic sequence (seen in 0.5% of HIV strains) that cause the viral genome to be cut by an enzyme used in the assay.

Can you please consult with your experts to find out exactly what this means. I'm pretty scared about having a virus that cannot be completely resistance tested. I know you advised that I have a genotype done, but still, I would like to know what is going on.

Thanks

Because of the way the PhenoSense assay is done, they cut a piece out of a patient's virus strain and insert it into a laboratory strain, in order to do the assay. It is likely you have some mutations at the point where your virus needs to be cut, and that is why they can't do the test. No worries, there are resistance tests (genotypic tests) from other vendors that will be able to be used with your virus strain.