The olfactory neuroepithelium, which lines the posterior nasal cavity, is exposed to a wide range of odorants and airborne toxic compounds. Odorants, which are mostly small lipophilic molecules, enter the mucus flow and reach the odorant receptors on sensory neurons. Odorant sensing is generally a transient process, requiring an effective signal termination, which could be provided by biotransformation of the odorant in the epithelial supporting cells. Xenobiotic-metabolizing enzymes in the olfactory epithelium have been suggested to catalyze inactivation and facilitate elimination of odorants.[5]UGT2A1 and UGT2A2 were recently implicated as having a role in the loss of smell symptom associated with COVID-19.[7]
^Mackenzie PI, Bock KW, Burchell B, Guillemette C, Ikushiro S, Iyanagi T, Miners JO, Owens IS, Nebert DW (October 2005). "Nomenclature update for the mammalian UDP glycosyltransferase (UGT) gene superfamily". Pharmacogenet. Genomics. 15 (10): 677–85. doi:10.1097/01.fpc.0000173483.13689.56. PMID16141793.
^Shelton, Janie F.; Shastri, Anjali J.; Aslibekyan, Stella; Auton, Adam; Auton, Adam (2021). "The UGT2A1/UGT2A2 locus is associated with COVID-19-related anosmia | medRxiv". medRxiv10.1101/2021.05.28.21257993v1.
