Beyond TAAR1, other TAAR subtypes (e.g., TAAR5, TAAR8, TAAR9) and their ligands (such as trimethylamine, cadaverine, and putrescine) also demonstrate dysregulated expression or metabolic disturbances in IBD patients [31], suggesting a broader involvement of the TAAR family in IBD pathogenesis. This evidence concerns the gene TAAR9 and inflammatory bowel disease.