CYP2B6*11 (c.136A>G, p.M46V) – Uncertain function: CYP2B6*11 is assigned uncertain function. In vitro studies using cDNA expression systems demonstrated decreased or no enzyme activity compared to the *1 reference (20517174, 21746968, 15190123, 30201214). Some studies with heterozygous and homozygous CYP2B6*11 patients showed that this allele is associated with increased exposure of efavirenz (27045425, 26779253, 28886044), while other clinical studies (25303294, 23734829, 19916993, 23778320) did not consistently demonstrate decreased enzyme activity or altered PK with efavirenz. Therefore, consensus among experts was uncertain function based on consistent in vitro data but limited and inconsistent clinical evidence.