Such a phenotype has already been observed in Hipk4 (homeodomain-interacting protein kinase 4) KO mice demonstrating that this gene is essential for murine spermiogenesis as a regulator of the shape of the sperm head [22], or in germ cell-specific Sirt1 KO infertile mice where disrupted spermiogenesis caused defects in acrosome biogenesis, which resulted in a phenotype similar to that observed in human globozoospermia [23]. Here, SIRT1 is linked to Globozoospermia.