MicroRNAs (miRNAs) are short non-coding RNAs consist of 20-24 nucleotides, it play major roles in all biological pathways in mammals and other multicellular organisms. it effected in numerous cancer-relevant processes like proliferation, cell cycle control, programed cell death, differentiation, migration and metabolism. The present study carried out to estimate Micr-RNA146a gene polymorphism in breast cancer tissue, about 30 sample of embedded tissue were collected after diagnostic it, also 30 sample of healthy blood were collected for comparison , micro-RNA gene was detected using PCR-SSCP technique, the results show that there were 4 haplotypes in this gene A,B,C,D . The Variations in these haplotypes appeared in A and D, haplotypes A and was appeared in 75%, and 100% in patients and control respectively, D disappeared in control but it was 100% in patients . The present study concluded that this gene can be conducted as risk factor in breast cancer, but it need more investigations to detect SNPs and sequencing of micro-RNA146a gene.

Keywords : Micr-RNA146a, gene polymorphism, breast cancer, PCR-SSCP.