Background: Cytochrome P450 (CYP) contributes to a huge collection of medicinal products' Phase I
metabolization. We aimed to summarize and investigate the current evidence regarding the frequency of CYP2D6,
CYP2C9, CYP2C19, MDR1 in Saudi Arabia.
Methods: A computerized search in four databases
was done using the relevant keywords. Screening process was done in
two steps; title and abstract screening and full-text screening. Data of demographic and characteristics of included studies
and patients was extracted and tabulated.
Results: Ten studies were eligible for our criteria and were included in this systematic review. Age of participants ranged
between 17-65 years. Only two subjects showed PM phenotype of CYP2C19 in Saudi population. The most frequent
alleles were CYP2C19*1 (62.9%), CYP2C19*2 (11.2%-32%), and CYP2C19*17 (25.7%). The CYP2C19m1 was observed
in 97 cases of extensive metabolizing (EM) phenotype CYP2C19. Concerning the CYP2C9, the most frequent alleles
were CYP2C9*1 and CYP2C9*2, and the most frequent genotype was CYP2C9*1*1. The CYP2D6*41 allele and
C1236T MDR1 were the most frequent allele in this population.
Conclusion: The current evidence suggests that Saudi Arabians resembled European in the frequency of CYP2C19,
Caucasians in both the incidence of CYP2C9 and CYP2C19m1 and absence of CYP2C19m2. The CYP2D6*41 allele
frequency in Saudi Arabians is relatively high. We recommend a further research to evaluate the basic and clinical
relevance of gene polymorphism in such ethnicity.