FOXP3 was reported to play important roles during regulatory T-cell development in previous studies (Gavin et al., 2007; Weigel et al., 1989), and FOXP3 polymorphisms are associated with human female endometriosis and male infertility (Brunkow et al., 2001; Piccirillo, 2020). Here, FOXP3 is linked to male infertility.