CYP2B6*17 (c.76A>T, p.T26S; c.83A>G, p.D28G; c.85C>A+c.86G>C, p.R29T) – Normal function: CYP2B6*17 is assigned normal function. A study evaluating efavirenz content in hair samples among HIV patients taking efavirenz for more than three months found that long term efavirenz exposure was not impacted by the CYP2B6*17 allele (26655325). Additionally, CYP2B6*17 had similar enzyme activity in vitro using cDNA expression systems compared to the *1 reference (16272958, 30201214, 32238417), but decreased activity for methadone (35538637). This discrepancy is probably due to differences in the in vitro expression systems and substrates used. Therefore, consensus among experts was normal function based on limited evidence.