Sperm derived from mice lacking any of the CatSper α 1–4 genes (Ren et al., 2001; Quill et al., 2003; Qi et al., 2007) as well as human males with mutations affecting CatSper function (Avidan et al., 2003; Avenarius et al., 2009; Smith et al., 2013) are unable to hyperactivate and therefore infertile. Here, CATSPER1 is linked to Infertility.