SMAP2 and Reduced sperm motility: In mammals, SMAP2 is necessary for spermiogenesis (Han et al., 2020), where SMAP2-deficient mice have been shown display male infertility (Sumiyoshi et al., 2015), globozoospermia (Funaki et al., 2013), asthenozoospermia (Funaki et al., 2013), and abnormal acrosome formation (Funaki et al., 2013).