With development of genomics and bioinformatics,especially the extensive applications of high-throughput sequencing technology,more transcriptional units with little or no protein-coding potential have been discovered.This RNA molecule is called nonprotein-coding RNA.Among them,lncRNA represents different class of transcripts.lncRNAs Xist important function is X-inactivation.In vertebrate genomes,male has XY,female has XX but only one of the X is active in female.LncRNA allow the cell to fine-tune the gene expression in response to its environment or to regulate completely silence a gene to make sure proper tissue patterning during embryonic development programs.