CYP2D6 allele frequency in European Caucasians, Asians, Africans and their descendants

Over 40 cytochrome P450 (CYP) 2D6 allelic variants have been discovered thus far. The alleles may be classified on the basis of the level of activity for which they encode CYP2D6 enzymes, into functional, non-functional and reduced function groups. CYP2D6 allele frequency is known to vary amongst racial/ethnic groups. Generally, for European Caucasians and their descendants, the functional group of alleles are predominant, with a frequency of 71%. Non-functional alleles represent 26% of the variability, mainly CYP2D6*4. In Asians and their close descendants, functional alleles represent only ~ 50% of the frequency of CYP2D6 alleles. Asians and Pacific Islanders have a high frequency (median = 41%) of a reduced…