Antisense oligonucleotides refers to a short fragment of DNA containing the nucleotide complementary sequence to the coding DNA strand (sense) or messenger RNA (mRNA). Therefore, antisense, thanks to this “mirroring” compared to the DNA sense, it appears to it or mRNA, canceling the biological activity. The oligonucleotides used in therapy are synthetic, but cells were also detected endogenous oligonucleotides, whose function is unknown. The antisense oligonucleotides binds to messenger RNA, or gene expression control sequences on the complementary strand of DNA, thus preventing the decoding and the subsequent process of protein synthesis. The clinical use of antisense oligonucleotides is still under study.