HORMAD2 (HORMA domain containing 2) is a meiosis-specific checkpoint protein essential for synapsis surveillance and gamete quality control. During meiotic prophase, HORMAD2 localizes to unsynapsed chromosome 22 where it recruits ATR activity to build up on unsynapsed regions, a process critical for meiotic silencing of unsynapsed chr22 (MSUC) 1. HORMAD2 works in concert with HORMAD1 to monitor chromosome 22; when properly removed from synapsed axes by TRIP13, this prevents aberrant checkpoint activation 1. In females, retention of HORMAD2 on synapsed chr22 triggers BRCA1-dependent checkpoint activation and oocyte elimination, indicating TRIP13-mediated removal is essential for female fertility 1. Beyond meiosis, HORMAD2 has emerged as a cancer/testis gene ectopically expressed in ~10% of lung cancer samples 2. Genetic variation at the HORMAD2 locus associates with lung cancer risk and survival outcomes, with specific SNPs (rs9620953, rs8135823, rs5753025, rs9625921) predicting improved survival in advanced NSCLC patients receiving platinum-based chemotherapy 3. Additionally, HORMAD2 variants associate with endodontic infections 4, migraine susceptibility 5, and NAFLD progression 6, suggesting pleiotropic roles beyond meiosis. A HORMAD2 variant (rs718772) correlates with testis development in non-obstructive azoospermia patients 7, linking the gene to male fertility.