HTR4 (5-Hydroxytryptamine Receptor 4, also known as 5-HT4R) is a Protein Coding gene. This gene is a member of the family of serotonin receptors, which are G protein-coupled receptors that stimulate cAMP production in response to serotonin (5-hydroxytryptamine). The encoded protein is a glycosylated transmembrane protein that functions in both the peripheral and central nervous system to modulate the release of various neurotransmitters. 5-HTR3 and 5-HTR4 were located in cardiac mitochondria, and regulated mitochondrial activities and cellular functions. Noncoding variants in HTR4 are associated with pulmonary function in human GWASs. The HTR4 gene is located in a region previously linked to an increased risk of asthma and atopy. SNP and haplotypes of the HTR4 gene were associated with the asthma phenotype and genetic variation of HTR4 may affect susceptibility to the development of asthma.