HOTAIR and male infertility: Regarding the eight lncRNAs identified to be differentially expressed in many sub-types of male infertility (Figure 9), HOTAIR (Hox transcript antisense intergenic RNA) is a well-studied lncRNA that plays an important role in tumor progression and development, as it is found to be overexpressed in many types of cancer [89], including breast cancer [90], lung cancer [91], hepatocellular carcinoma [92], etc. In male infertility, HOTAIR was found to be downregulated in patients with asthenozoospermia [35,41] and oligoasthenozoospermia [35].