UTY is a Y-chrY-encoded histone demethylase that catalyzes H3K27me3 demethylation 1, though it exhibits weaker enzymatic activity compared to its X-chromosome Y UTX 2. Beyond its canonical demethylase function, UTY forms phase-separated liquid condensates that mediate chrY regulation, though with reduced molecular dynamics relative to UTX 2. In spermatogenesis, UTY plays a critical role in regulating spermatogonial proliferation and is part of the AZFa locus essential for male fertility 31. UTY undergoes exceptional alternative splicing generating over 1.3 billion theoretical transcripts, contributing unique protein isoforms with distinct interactors 4. Clinically, UTY serves as a male-specific minor histocompatibility antigen presenting HLA-B8-restricted epitopes 5, relevant in sex-mismatched transplantation. While mutations in its X-linked paralog KDM6A cause Kabuki syndrome type 2, screening of male patients has not identified comparable UTY mutations as a disease cause 6. UTY's functional importance is evidenced by its conservation across mammalian species and its role in normal gonadal development, contrasting with earlier assumptions of functional redundancy with UTX 7.