Background: The Cytochrome P450 (CYP) enzymes are involved in the metabolism of many endogenous
and exogenous substances. They need electrons for their activity. CYP mediated oxidation reactions require cytochrome
oxidoreductase (POR) as an electron donor. A common genetic variation identified in the coding region of
POR gene (POR*28) leads to an alteration in POR activity by causing amino acid change. The current study aimed to
determine the allele and genotype frequencies of POR*28 in a healthy Turkish population by using a novel genotyping
Methods: A novel PCR-RFLP assay was developed for the detection of POR*28 (rs1057868) polymorphism and the
obtained frequencies were compared with the data established in various ethnic groups.
Results: Genotypic analysis revealed that of 209 healthy, unrelated individuals tested for POR*28 polymorphism,
55.5% of the studied subjects were homozygous for the CC genotype, 34.9% were heterozygous for the CT genotype
and 9.6% were homozygous for the TT genotype. The allele frequencies were 0.73 (C) and 0.27 (T). The present
results were in accordance with the Hardy- Weinberg equilibrium. The distribution of POR*28 allele varies between
populations. The frequency of the T allele among members of the Turkish population was similar to frequencies in
Caucasian populations but was lower than in Japanese and Chinese populations.
Conclusions: In this study, a novel method was developed, which could be applied easily in every laboratory for the
genotyping of POR *28 polymorphism. The developed genotyping method and documented allele frequencies may
have potential in understanding and predicting the variations in drug response/adverse reactions in pharmacotherapy
and susceptibility to diseases in POR-mediated metabolism reactions.