Background: Myelodysplastic syndromes (MDSs) are a heterogeneous group of disorders characterized by clonal disorder and ineffective hematopoiesis. Cytogenetic abnormalities can be detected in approximately 50% of patients with de novo MDS and are one of the main keys of prognostic factor. On the other hand, miRNAs that regulate gene expression of complementary mRNAs are crucial key of cellular processes which their deregulation is implicated in the disease development and progression. The purpose of this study is to assess cytogenetic and expression of miRNA let-7a and its target gene NRAS in order to find whether any correlation between IPSS based on cytogenetic and expression of this microRNA and gene in patients does exist. Method: In this study the 21 patients with de novo MDS between were selected, and 25 control groups were healthy people. Chromosomal analysis of lymphocyte cultures were performed on the basis of G-banding technique at high resolution. For molecular analysis: RNA extraction, cDNA synthesize, survey expression of microRNA by real-time quantification PCR were applied. Results: Twenty patients appear with a normal karyotype whereas only one patient revealed the constitutive heterochromatic region below the centromeres of chromosomes 1 (46,XX(1qh+)). The expression of the Let-7a miRNA was decreased whereas its target NRAS gene was increased in our patients as compared with the controls group (P value <0.0001). Conclusion: According to decreasing expression of miRNA let-7a and increasing expression of NRAS in MDS patients, we suggest, using miRNA, molecular and cytogenetic panel as a prognostic marker in MDS patients. Future studies are needed to confirm it.
