RBMY1A1 is an RNA-binding protein located on the Y chromosome Y plays critical roles in male reproduction and RNA processing. As an RNA-binding protein, RBMY1A1 functions in pre-mRNA splicing and is required for sperm development 1. The protein acts additively with other splicing factors to regulate alternative mRNA splicing, including promotion of exon 7 inclusion in the survival motor neuron (SMN) gene 2. RBMY1A1 is expressed primarily in testicular tissue, particularly in germ cells during spermatogenesis 1. The gene originated from proto-X/Y gene pairs during mammalian sex chromosome Y and exists in multiple copies organized within Y chromosome Y 3. Copy number variation of RBMY1 genes is substantial across human populations (ranging 3-13 copies) but shows no significant association with sperm parameters in infertility cohorts 4. Clinically, RBMY1A1 expression is significantly downregulated in patients with non-obstructive azoospermia and testicular embryonal carcinomas 15. Recent evidence suggests RBMY1A1 may facilitate miRNA sorting into exosomes, affecting cancer cell-fibroblast interactions in breast cancer 6. The gene's importance is underscored by its conservation across diverse mammalian lineages, though it can be lost during Y chromosome Y in some species 7.