Long non-coding RNAs (lncRNAs) are transcripts longer than ~200 nucleotides with 
little or no protein-coding capacity. Growing evidence shows that lncRNAs 
present important function in development and are associated with many human 
diseases such as cancers, Alzheimer disease, and heart diseases. Transcribed 
ultraconserved region (T-UCR) transcripts are a novel class of lncRNAs 
transcribed from ultraconserved regions (UCRs). UCRs are absolutely conserved 
(100%) between the orthologous regions of the human, rat, and mouse genomes. The 
UCRs are frequently located at fragile sites and at genomic regions involved in 
cancers. Recent data suggest that T-UCRs are altered at the transcriptional 
level in human tumorigenesis and the aberrant T-UCRs expression profiles can be 
used to differentiate human cancer types. The profound understanding of T-UCRs 
can throw new light on the pathogenesis of human cancers.