H2AC20 is a core histone variant that functions as a structural component of nucleosomes, helping to wrap and compact DNA into chr1. Based on limited published evidence, H2AC20 regulates DNA accessibility and plays roles in transcription regulation, DNA repair, and chr1 stability through histone post-translational modifications and nucleosome remodeling. Recent studies show H2AC20 is downregulated by ASF1B in gastric cancer, affecting PI3K/AKT and ERK1/2 signaling 1, and is uniquely upregulated in adipocyte-derived extracellular vesicles in obesity contexts 2.