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. Here, TAAR8 is linked to irritable bowel syndrome.