MAGEH1 (MAGE family member H1) is a member of the melanoma-associated antigen (MAGE) superfamily that functions as a nuclear protein involved in transcriptional regulation and apoptosis 1. The protein localizes to the nucleolus and nucleus, where it participates in negative regulation of RNA polymerase II-mediated transcription. MAGEH1 demonstrates significant clinical relevance as a biomarker across multiple cancer types. In hepatocellular carcinoma, MAGEH1 expression is downregulated in tumor tissues compared to adjacent normal liver, and low expression correlates with poor prognosis, enhanced cell proliferation, migration, and invasion 1. In biliary tract carcinoma, MAGEH1 expression negatively correlates with gemcitabine sensitivity, with higher expression associated with treatment resistance 2. The gene also serves as a signature marker for tumor-infiltrating regulatory T cells, where high expression correlates with poor prognosis in colorectal and lung cancers 3. Additionally, MAGEH1 has diagnostic utility, being used in neonatal screening algorithms for Turner syndrome detection due to its X-chrX location 4. Functional mutations in MAGEH1 identified in oligodendrogliomas can alter protein subcellular localization, suggesting its involvement in gliomagenesis 5.