CYP2B6*15 (c.1172T>A, p.I391N) – Uncertain function: CYP2B6*15 is assigned uncertain function. In vitro studies using human liver microsomes (17559344, 15190123) and cDNA expression systems (15190123, 20517174, 21746968, 30201214) showed decreased to no enzyme activity for CYP2B6*15 compared to the *1 reference (20662624). However, due to the lack of any in vivo or clinical evidence, consensus among experts was uncertain function based on limited evidence.