The associations between 6-n-propylthiouracil (PROP) intensity and taste intensities differ by TAS2R38 haplotype

Background/Aims: The influence of TAS2R38 haplotype on the relationship between the perceived intensity of propylthiouracil (PROP) and the basic tastes of salt, sweet, sour, and bitter (quinine) was evaluated in the Beaver Dam Offspring Study. Methods: Genotyping was performed on 1,670 participants aged ≥45 years (mean age = 54.4; range = 45-84), and suprathreshold taste intensity was measured using filter paper disks and a general labeled magnitude scale (0-100). Results: Among those with taste intensity data and the PAV or AVI haplotype (n = 1,258), the mean perceived intensity of PROP was 37.3 (SD = 30.0), but it varied significantly (p < 0.0001) by diplotype (PAV/PAV = 60.1; PAV/AVI = 46.5; AVI/AVI = 14.4). PROP intensity was correlated with the basic taste intensities (salt: r = 0.22; sweet: r = 0.25; sour: r = 0.21; quinine bitterness: r = 0.38; p < 0.001 for all tastes); however, a significant effect modification of the PROP-taste intensity relationships by TAS2R38 diplotype was observed. There was a stronger association between PROP and each of the basic tastes in the PAV/PAV diplotype group than in the other groups. Conclusions: Directly measuring the perceived intensity of the 4 tastes, rather than using PROP intensity as an indicator of taste responsiveness, is recommended for studies of taste perception.