Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. Its various actions are mediated by a family of histamine receptors, which are a subset of the G-protein coupled receptor superfamily. This gene encodes a histamine receptor that is predominantly expressed in haematopoietic cells. The protein is thought to play a role in inflammation and allergy reponses. Multiple transcript variants encoding different isoforms have been found for this gene.HRH4 (Histamine Receptor H4) is a Protein Coding gene. Diseases associated with HRH4 include Paraneoplastic Cerebellar Degeneration and Allergic Hypersensitivity Disease. Among its related pathways are Peptide ligand-binding receptors and CCR5 Pathway in Macrophages. GO annotations related to this gene include G-protein coupled receptor activity and histamine binding. An important paralog of this gene is HRH3.