CYP2B6*10 (c.62A>T, p.Q21L and c.64C>T, p.R22C) - Uncertain function: CYP2B6*10 is assigned uncertain function. In vitro studies using cDNA expression systems (21746968, 30201214) demonstrated decreased enzyme activity compared to the *1 reference. However, consensus among experts was uncertain function based on inadequate evidence as it could not be determined if diplotypes containing this allele would be phenotypically distinct from diplotypes comprising two normal function alleles.