MACROH2A1 (MacroH2A.1 Histone, also known as H2AFY) is a Protein Coding gene. 3 alternatively spliced human isoforms have been reported. This gene encodes a replication-independent histone that is a member of the histone H2A family. It replaces conventional H2A histones in a subset of nucleosomes where it represses transcription and participates in stable X chromosome inactivation. H2AFY is widely expressed in bone marrow, esophagus, and other tissues. Diseases associated with MACROH2A1 include Liebenberg Syndrome and Medulloblastoma. H2AFY is a potential biomarker associated with disease activity and pharmacodynamic response that may become useful for enabling disease-modifying therapeutics for Huntington's disease (HD). An important paralog of this gene is MACROH2A2.