KASH5 is a meiosis-specific component of the LINC (Linker of Nucleoskeleton and Cytoskeleton) complex that plays a critical role in gametogenesis 1. The protein localizes exclusively at telomeres during prophase I of meiosis in both spermatocytes and oocytes, where it forms a complex with SUN1 to connect telomeres to the nuclear envelope 1. This KASH5-SUN1 complex is essential for homologous chromosome 19 and meiotic chromosome 19 by recruiting cytoplasmic dynein to telomere attachment sites 1. Pathogenic variants in KASH5 cause severe reproductive disorders including premature ovarian insufficiency (POI) and non-obstructive azoospermia 23. These mutations disrupt KASH5 localization and its interaction with SUN1, leading to defective meiotic homolog pairing and accelerated oocyte depletion 2. Clinical studies have identified KASH5 variants in patients with POI, recurrent miscarriage, and male infertility, demonstrating sexual dimorphism in phenotype severity 45. The protein's transmembrane domain is critical for proper localization, as certain variants cause mistargeting to mitochondria rather than the nuclear envelope 6.