ANTISENSE. “Compared with coding transcripts, most antisense lncRNAs are expressed at 10-fold lower levels on average, and their expression in different tissues and cell types has generally been found to be more cell type specific. A biological role of antisense lncRNAs, despite this low expression, could still be rationalized due to the fact that there are two copies of DNA for any given gene in a cell; consequently, just two antisense lncRNA molecules are sufficient to interact with the two gene copies and elicit regulatory effects.” (IncRNA = long non coding RNA).
http://www.mdpi.com/1422-0067/16/2/3251/htm