Pseudo-cholinesterase polymorphism in Mazandaran province (North of Iran)

Background: Pseudocholinesterase (PChE) polymorphism has been a subject of several pharmacogenetic studies worldwide. The patients with atypical homozygous genotype do not only have reduced serum cholinesterase activities but also their elimination rate for some pharmacologically potent drugs decrease drastically. This study was designed to evaluate the PChE polymorphism in Mazandaran province (northern Iran) for the first time. Methods: About 5 ml plasma samples were collected from 200 healthy volunteers who visited "Iran Blood Transfusion Organization" centers all across Mazandaran province for blood donation. The PChE activity in presence or absence of dibucain was measured and based on obtained dibucain number (DN) volunteers were categorized to normal homozygous (Eu,u), atypical heterozygous (Eu,a), and atypical homozygous (Ea,a). Results: The average (±SD) of the PChE activity among the blood donors was 9.14 ± 1.93 IU (ranging from 4.1 to 16.6 IU). Only 2 persons (1%) had DN between 60 to 70 (Eu,a) and no one was categorized in 20<DN<30 (Ea,a) group. Nine volunteers (4.5%) in normal group (Eu,u) had DN values less than 72. The within- run and between run-precisions (CV) for DN measurements in our laboratory were found to be 2% and 4%, respectively. Conclusion: According to the findings, only 1% of the sample population had atypical heterozygous phenotype taking into account the experiment precision, the frequency of Ea,u is less than 4%. These findings suggest that the atypical allele frequency in northern Iran's population is probably less than the other regions of Iran and some other countries.