Antisense therapy is a form of treatment for a broad range of diseases caused or maintained by aberrant gene expression. The genetic information of a cell is stored in the form of a double-stranded DNA in the nucleus. In a process known as transcription, genetic information stored in the DNA is transcribed into RNA. The resulting RNA can either have regulatory functions or code for proteins. ASOs are synthetic, chemically modified, short, single-stranded DNA sequences complementary to the aberrantly expressed target RNA and are designed to specifically bind only to their target RNA. Chemical modifications increase stability against degradation as well as cellular uptake and binding affinity to the target, and reduce unwanted side effects. After the ASO binds to the target RNA, the target RNA is degraded by cellular mechanisms and cannot exert its regulatory functions or be translated into proteins that promote development and progression of diseases.