Olfactory receptor gene ([https://senselab.med.yale.edu/ordb/ OR]) is normally expressed in human and mouse olfactory tissue with a main function as odorant receptor for the detection of odorants. Individuals with a defect in this gene have disorders of taste and smell. It has been reported that ORs is also expressed on sperms and testis with special emphasis in a manner of ectopic expression. In a study, researchers identified ectopic expression of OR genes in non-olfactory tissues in the mouse model by measuring transcript levels. Here they found relatively low OR gene expression compared to the olfactory tissue, which result indicates that the OR gene in other tissue have no extra function, but they suggest that there is a possibility that small OR subsets can have functional roles in different tissue.