ZPBP and Azoospermia: Deleted in azoospermia (DAZ) and testis-specific protein Y-linked 1 (TSPY1) genes have been found to be expressed at the pre-meiotic stage, whereas transition protein 1 (TNP1), protamine 2 (PRM2), synaptojanin 2 (SYNJ2), and zona pellucida binding protein (ZPBP) genes are expressed particularly at the post-meiotic stage [66].