CATSPER1 and Infertility: In addition, mutations in the genes encoding CatSper subunits, such as CatSper1 (Avenarius et al., 2009), CatSper2 (Avidan et al., 2003; Smith et al., 2013; Luo et al., 2019; Schiffer et al., 2020), and CatSperε (Brown et al., 2018), have been identified in infertile males whose sperm failed to develop hyperactivated motility (Schiffer et al., 2020; Young et al., 2023).