“…Previous study reported the prevalence of CYP2D6*10 as ~9.0% in Iranian Azerbaijanis (26), but another study of Iranians of different ethnicities reported the prevalence of the allele to be 39.3% (24.3% for homozygous T/T and 15.0% for heterozygous C/T) (25). The frequency of CYP2D6*4 varies across different races, and frequencies of 36.6, 28.6, 28.0, 13.8, 13.8, 7.3 and 0.2% have been reported in Iranians, Malaysian Indians, Turks, Spanish subjects, Brazilians, South-Indians and North Americans, respectively (18,(36)(37)(38)(39)(40)(41). Conversely, the frequency of CYP2D6*4 varies from 0.2 to 3.5% among Japanese, Chinese and Saudi Arabians, which is considered relatively low (20)(21)(22).…”