Role of the TAS2R38 Bitter Taste Receptor Gene Single Nucleotide Polymorphism in Patients With Taste Disorders

Background and Objectives Several studies have shown that three single nucleotide polymorphisms (SNPs) in the TAS2R38 gene demonstrate a strong association with the ability to sense the bitter taste of phenylthiocarbamide (PTC) in. We have previously reported about TAS2R38 genotypes in normal volunteers. The aim of this study was to investigate the role TAS2R38 gene plays in taste disorder by examining SNPs in the TAS2R38 gene in taste disorder patients.Subjects and Method Ninety-four patients with taste dysfunction from multiple etiologies were enrolled. The genotypes were defined by identifying SNPs on the TAS2R38 gene. The proportion of different TAS2R38 genotypes in the group was compared with that in the normal volunteers of our previous study. The whole mouth taste threshold tests were performed and the thresholds were compared among the three different genotypic groups.Results The proportion of each diplotype in taste disorder patients were as follows: PAV/ PAV 36.2% (34/94), PAV/AVI 34.0% (32/94), and AVI/AVI 29.8% (28/94). The proportion of AVI/AVI type was higher in the group than in the normal volunteers (p=0.031). The detection and recognition thresholds of all four basic tastes were increased in the order of PAV/PAV, PAV/AVI, and AVI/AVI genotypes.Conclusion The proportion of AVI/AVI homozygous was significantly higher in taste disorder patients than in the normal volunteers. Our findings suggest that the genotypes of TAS2R38 may represent one of the risk factors responsible for the development of taste disorders.

The correlation of TAS2R38 gene variants with higher risk for chronic rhinosinusitis in Polish patients

Background: Bitter taste receptors (T2Rs), especially T2R38s appear as innovative regulators of innate immunity in the respiratory system. The single nucleotide polymorphisms (SNPs) in TAS2R38 gene may contribute to individual differences in susceptibility to respiratory infections especially chronic rhinosinusitis (CRS). TAS2R38 genotypes distribution varies by geographic region, race and ethnicity. The aim of the preliminary study was the identification of SNPs in TAS2R38 encoding genes in Polish patients with CRS and finding potential correlation with CRS phenotypes. Material and methods: The preliminary study contained 20 CRS patients undergoing functional endoscopic sinus surgery (FESS). Fresh sinus mucosa (SM) was obtained during FESS in CRS patients. Patients were genotyped for TAS2R38 using Sanger method and the genotype occurrences of the clinically recalcitrant CRS cohort was evaluated. Analysis of TAS2R38 expression in SM of CRS patients was performed using immunohistochemistry (IHC). Results: T2R38 was highly expressed in SM of CRS patients. Patients with CRS demonstrated both common genotypes PAV, AVI. The heterozygotes frequency (AVI/PAV) was the highest. The protective genotype (PAV/PAV) was noticed in the lowest frequency and connected with lower average value of CT score compare to AVI/AVI genotypes (p=0.01). Conclusions: The work presented in this study provides the hypothesis that airway bitter T2Rs are an innovative sphere of human respiratory innate protection. TAS2R38 polymorphism may influence the susceptibility to CRS. The AVI haplotypes are an independent risk factors for CRS. Additionally, the bitter taste receptors and related signalling pathways might create an unique group of therapeutic targets to treat CRS.