SIX6OS1 (SIX6 Opposite Strand 1) is a nuclear protein that plays a core role in the process of meiosis. It is a key scaffold protein that constitutes the central element of the synaptonemal complex, directly interacting with proteins such as SYCE1 to ensure the proper pairing, synapsis, and genetic recombination of homologous chromosomes. Its function is crucial for the formation of stable chiasmata, which are the basis for genetic diversity and the accurate segregation of chromosomes. Mutations in the SIX6OS1 gene can disrupt this process, leading to errors in chromosome separation and are one of the important genetic factors causing primary ovarian insufficiency in humans and non-obstructive azoospermia in males, directly associated with reproductive disorders.