
Single nucleotide polymorphism (SNP) in multidrug resistance gene1 (MDR1) could alter the gene expression level and may have effect role in responses to drug therapy and diseases susceptibility. The aim of the present study is to investigate allele frequency in Iraqi healthy and AML patients to detect the susceptibility of C3435T genotype carrier to develop acute myeloid leukemia. Also the study aimed to correlate the expression level of MDR1 mRNA with MDR1 gene and C3435T polymorphism in de novo AML patients. The results showed there was a significant difference in genotype and allele frequency with heterozygous CT and mutant T-allele. The results also showed that there was no significant difference between genotype and allele frequency in healthy control and AML patients. According to the clinical outcome status MDR1 3435CT showed statistically high significant differences, while CR group was showed significantly with homozygous TT. Both NR and CR group in AML patients showed high mutant-T allele frequency. In regard with gene expression, the healthy control showed significantly high level of MDR1 mRNAs expression in CC genotype at position 3435 compared with CT and TT. Whereas MDR1 heterozygous 3435CT genotype showed a highly significant difference in MDR1 mRNA expression among AML patients. In conclusion healthy Iraq populations and AML patients have predominantly CT genotype and mutant-T allele frequency for MDR1 C3435T polymorphism. MDR1 3435CT/TT genotype in regard with MDR1gene expression in de novo AML patients associated with poor prognosis, while CC genotype was protective Carrier.