Objective    To study the correlation between multidrug resistance gene 1 (MDR1) C3435T polymorphism and its mRNA expression in peripheral blood mononuclear cells of healthy Han populations.     Methods    A total of 130 Chinese Han healthy children at a mean age of 7.62 with no consanguinity (83 males and 47 females) were included in this study. Genotypes of MDR1 C3435T polymorphism were identified by PCR-RFLP

and MDR1 mRNA expression levels in peripheral blood mononuclear cells were measured by SYBR green Ⅰ real-time polymerase chain reaction.     Results    The CC

CT and TT genotypes of MDR1 C3435T polymorphism were identified in 51

63

and 16 out of the 130 children

respectively. The distribution of genotypes was consistent with the Hardy-Weinberg equilibrium (P0.05). No significant difference was found in MDR1 mRNA expression levels between the CC

CT and TT genotypes of MDR1 C3435T polymorphism in peripheral blood mononuclear cells.     Conclusion    MDR1 C3435T polymorphism does not significantly influence its mRNA expression in peripheral blood mononuclear cells of Chinese Han children. Genotyping of this polymorphism cannot be used as the evidence for predicting the expression of MDR1 in Chinese Han children.