Abstract: The present invention relates to substantially single-stranded isolated RNA molecules comprising 18 to 19 contiguous nucleotides that corresponds to a non-protein-coding genomic DNA sequence located between ?60 and +120 nucleotides from a transcription start site in a mammalian genome. Specifically, the isolated RNA molecules have a high GC content (>60%), are nuclear specific, and may be associated with aberrant gene regulation and/or transcription in various mammalian diseases and conditions. The isolated RNA molecules, modified RNA molecules and fragments thereof may be particularly useful for the diagnosis, prognosis and treatment of diseases such as Crohn's disease, Alzheimer's disease, Parkinson's disease, rheumatoid arthritis, myocardial infarction, diabetes, congenital developmental disorders, coronary heart disease and cancer such as breast cancer, lymphoma, leukemia, aggressive metastatic brain cancers, colorectal cancer, gastric cancer, ovarian cancer and pituitary tumors.