Zhang C, et al. - Researchers examined how the CHL1 gene (close homologue of L1 or cell adhesion molecule L1 like, a member of the L1 gene family of neural cell adhesion molecules and belongs to immunoglobulin superfamily) is correlated to the long non-coding RNAs (lncRNAs), ie, CHL1-AS1 and CHL1-AS2 in ovarian endometriosis (EM). Further, they sought to validate the expression patterns of CHL1 and CHL1-AS2 in ovarian EM. As per previous microarray analyses (GSE86534) of 4 patients with ovarian EM, the most upregulated mRNA was CHL1 in ectopic endometrium (EC) compared with eutopic endometrium (EU) tissues; its two antisense lncRNAs CHL1-AS1 and CHL1-AS2, exhibited the same expression pattern. EC tissues vs EU and normal endometrium (NE) tissues had significantly higher CHL1 and CHL1-AS2 expression levels as per quantitative real-time polymerase chain reaction, while EU and NE tissues were not significantly different regarding these levels. In EC compared with EU tissues, they identified that the relative expression levels of CHL1 and CHL1-AS2 were positively significantly correlated. EC tissues showed elevated expression of CHL1 protein in western blotting. Ectopic endometrial glands and stroma had enhanced CHL1 protein expression levels as per IHC. These findings suggest that CHL1, CHL1-AS1 and CHL1-AS2 are significantly correlated, which might be involved in the development of ovarian EM.