title: Is the Association Between Sweet and Bitter Perception due to Genetic Variation?
abstract: Perceived intensities of sweetness and bitterness are correlated with one another and each is influenced by genetics. The extent to which these correlations share common genetic variation, however, remains unclear. In a mainly adolescent sample ( n = 1901, mean age 16.2 years), including 243 monozygotic (MZ) and 452 dizygotic (DZ) twin pairs, we estimated the covariance among the perceived intensities of 4 bitter compounds (6- n -propylthiouracil [PROP], sucrose octa-acetate, quinine, caffeine) and 4 sweeteners (the weighted mean ratings of glucose, fructose, neohesperidine dihydrochalcone, aspartame) with multivariate genetic modeling. The sweetness factor was moderately correlated with sucrose octa-acetate, quinine, and caffeine ( rp = 0.35-0.40). This was mainly due to a shared genetic factor ( rg = 0.46-0.51) that accounted for 17-37% of the variance in the 3 bitter compounds' ratings and 8% of the variance in general sweetness ratings. In contrast, an association between sweetness and PROP only became evident after adjusting for the TAS2R38 diplotype ( rp increased from 0.18 to 0.32) with the PROP genetic factor accounting for 6% of variance in sweetness. These genetic associations were not inflated by scale use bias, as the cross-trait correlations for both MZ and DZ twins were weak. There was also little evidence for mediation by cognition or behavioral factors. This suggests an overlap of genetic variance between perceptions of sweetness and bitterness from a variety of stimuli, which includes PROP when considering the TAS2R38 diplotype. The most likely sources of shared variation are within genes encoding post-receptor transduction mechanisms common to the various taste G protein-coupled receptors.
authors: QIMR Berghofer Medical Research Institute , Brisbane , Queensland 4006 , Australia.|School of Medicine , University of Queensland , Brisbane , Queensland 4006 , Australia.
authors: Liang-Dar
authors: LD
authors: Hwang
authors: Monell Chemical Senses Center , Philadelphia, PA 19104 , USA.|Department of Nutritional Sciences , School of Environmental and Biological Sciences , Rutgers University , New Brunswick , NJ 08901 , USA.
authors: Paul A S
authors: PAS
authors: Breslin
authors: Monell Chemical Senses Center , Philadelphia, PA 19104 , USA.
authors: Danielle R
authors: DR
authors: Reed
authors: QIMR Berghofer Medical Research Institute , Brisbane , Queensland 4006 , Australia.
authors: Gu
authors: G
authors: Zhu
authors: QIMR Berghofer Medical Research Institute , Brisbane , Queensland 4006 , Australia.
authors: Nicholas G
authors: NG
authors: Martin
authors: Queensland Brain Institute , University of Queensland , Brisbane , Queensland 4072 , Australia and.|Centre for Advanced Imaging , University of Queensland , Brisbane , Queensland 4072 , Australia.
authors: Margaret J
authors: MJ
authors: Wright
keywords: IQ; TAS2R38; personality; sweetener; taste; twins