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1.  Underlying genetic structure impacts the association between CYP2B6 polymorphisms and response to efavirenz and nevirapine 
AIDS (London, England)  2012;26(16):2097-2106.
Objective
CYP2B6 variation predicts pharmacokinetic characteristics of its substrates. Consideration for underlying genetic structure is critical to protect against spurious associations with the highly polymorphic CYP2B6 gene.
Design
The effect of CYP2B6 variation on response to its substrates, nonnucleoside reverse transcriptase inhibitors (NNRTIs), was explored in the Women's Interagency HIV Study.
Methods
Five putative functional polymorphisms were tested for associations with virologic suppression within one year after NNRTI initiation in women naïve to antiretroviral agents (n=91). Principal components (PCs) were generated to control for population substructure. Logistic regression was used to test the joint effect of rs3745274 and rs28399499, which together indicate slow, intermediate, and extensive metabolizers.
Results
Rs3745274 was significantly associated with virologic suppression (OR=3.61, 95% CI 1.16-11.22, p trend=0.03); the remaining polymorphisms tested were not significantly associated with response. Women classified as intermediate and slow metabolizers were 2.90 (95% CI 0.79-12.28) and 13.44 (95% CI 1.66-infinity) times as likely to achieve virologic suppression compared to extensive metabolizers after adjustment for PCs (p trend=0.005). Failure to control for genetic ancestry resulted in substantial confounding of the relationship between the metabolizer phenotype and treatment response.
Conclusion
The CYP2B6 metabolizer phenotype was significantly associated with virologic response to NNRTIs; this relationship would have been masked by simple adjustment for self-reported ethnicity. Given the appreciable genetic heterogeneity that exists within self-reported ethnicity, these results exemplify the importance of characterizing underlying genetic structure in pharmacogenetic studies. Further follow-up of the CYP2B6 metabolizer phenotype is warranted given the potential clinical importance of this finding.
doi:10.1097/QAD.0b013e3283593602
PMCID: PMC3940150  PMID: 22951632
CYP2B6; population substructure; women; NNRTIs; confounding
2.  Absence of reproducibly detectable low-level HIV viremia in highly exposed seronegative men and women. 
AIDS (London, England)  2011;25(5):619-623.
Objective
Transient HIV infections have been invoked to account for the cellular immune responses detected in highly virus-exposed individuals who have remained HIV seronegative. We tested for very low levels of HIV RNA in 524 seronegative plasma samples from 311 highly exposed women and men from 3 longitudinal HIV cohorts.
Design
2073 transcription mediated amplification (TMA) HIV RNA tests were performed for an average of 3.95 TMA assays per plasma sample. Quadruplicate TMA assays, analyzing a total of 2 ml of plasma, provided an estimated sensitivity of 3.5 HIV RNA copies/ml.
Results
Four samples from subjects who did not sero-convert within the following six months were positive for HIV RNA. For one sample, human polymorphism DNA analysis indicated a sample mix up. Borderline HIV RNA detection signals were detected for the other three positive samples and further replicate TMA testing yielded no positive results. Nested PCR assays (n=254) for HIV proviral DNA on PBMC from these 3 subjects were negative.
Conclusions
Transient viremia was not reproducibly detected in highly HIV exposed seronegative men and women. If transient infections do occur, plasma HIV RNA levels may remain below the detection limits of the sensitive assay used here, be of very short duration, or viral replication may be restricted to mucosal surfaces or their draining lymphoid tissues.
doi:10.1097/QAD.0b013e3283440269
PMCID: PMC3458706  PMID: 21297421

Results 1-2 (2)