ZP1 (zona pellucida glycoprotein 1) is a structural component of the zona pellucida, the extracellular matrix surrounding oocytes that mediates sperm-egg interactions and prevents polyspermy 1. ZP1 is one of three to four glycoproteins (ZP1-4) that assemble into interconnected filaments through a ZP domain 12. The protein ensures structural integrity of the zona pellucida and contributes to acrosome reaction induction; ZP1 binds capacitated spermatozoa and dose-dependently increases acrosome reaction 2. Following fertilization, ZP1 filaments become cross-linked and rigidified as part of the zona reaction, physically blocking supernumerary sperm penetration 3. Mutations in ZP1 cause oocyte maturation arrest and female infertility 4. Pathogenic variants impair ZP protein polymerization or secretion, preventing proper zona pellucida assembly 567. Clinical manifestations include empty follicle syndrome (failure to retrieve oocytes despite normal follicle development) and absence of zona pellucida around oocytes 56. Both homozygous and heterozygous mutations have been identified; some heterozygous cases respond to intracytoplasmic sperm injection (ICSI) 7. Genetic diagnosis of ZP genes enables appropriate reproductive counseling and selection of assisted reproductive technology strategies.