A polymorphism in the gene encoding AdipoR1 affects olfactory recognition

Polymorphisms in the gene encoding adiponectin receptor 1 (AdipoR1) are associated with insulin resistance, fatty liver, increased risk for type 2 diabetes and cardiovascular disease. AdipoR1 is expressed in the central nervous system and in the olfactory mucosa of mice and humans. We therefore hypothesized that a common polymorphism in AdipoR1 might alter olfactory function. We investigated a group of 222 healthy subjects (male: n = 147, female: n = 75) for olfactory recognition, and genotyped them for the polymorphism rs6666089 in the human AdipoR1 gene. This polymorphism has been previously shown to be associated with insulin resistance. Olfactory recognition was tested using standardized sniffing sticks, and parameters of glucose metabolism and serum adiponectin levels were assessed. We found a significant olfactory impairment in carriers of the AdipoR1 polymorphism rs6666089 (olfactory recognition: GG: 89.4 ± 1.2%, GA: 86.9 ± 1.4%, AA: 77.2 ± 4.8%, additive model, P = 0.0004, adjusted for age). Adiponectin levels had no impact on olfactory recognition. Fasting plasma glucose, fasting plasma insulin, body mass index and HbA1c did not differ between the genotype groups. In conclusion, the presence of a genetic variation in AdipoR1 is associated with decreased olfactory recognition in healthy subjects. Adiponectin signalling may have an important role in olfactory function and regulation of appetite.