Background/Aims:TAS2R38 belongs to the TAS2R bitter taste receptor gene family and polymorphisms are associated with differences in bitter taste perception of phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP). The objectives were to test whether the genotype-phenotype relationship varies between ethnocultural groups and whether a filter paper method can predict TAS2R38 genotype. Methods: Subjects (n = 911) aged 20–29 rated the intensity of a PTC-containing filter paper on a scale of 1–9, from ‘not at all bitter’ to ‘extremely bitter’. The TAS2R38 A49P polymorphism was detected by real-time PCR. Results: The overall frequency of the 49A variant was 0.47 and the AA, AP, and PP genotype distribution was 0.24, 0.45 and 0.31, respectively. Those with AA, AP, or PP genotypes had mean bitterness rating scores of 2.3, 4.9, and 5.9, respectively. The 49A variant frequency was significantly lower among Asians (28%) as compared to Caucasians (55%), South Asians (60%) or others (56%) (p < 0.0001). The genotype-phenotype relationship was similar across ethnocultural groups, however, a stronger genotype-phenotype association was observed among women as compared to men. Conclusion: Our findings show that a simple PTC filter paper tasting method strongly predicts TAS2R38 genotype, and that the genotype-phenotype association is similar among ethnocultural groups.

Individual differences in the ability to detect bitter tasting compounds, such as phenylthiocarbamide (PTC) or its derivative, 6-n-propylthiouracil (PROP) has long been recognized as a common genetic trait. This observation has been proposed to explain some of the variability in the dietary habits of a population. Several members of the TAS2R receptor gene family encode taste receptors on the tongue, and genetic polymorphisms of TAS2R38 have been associated with marked differences in the perception of PTC and PROP. An association between TAS2R38 genotype and food preferences has been found among children, but no associations have been reported among older adults. This, along with the decreased ability to taste certain foods with increasing age, suggests that environmental factors are more important than genetic influences in food preferences among the elderly. The elderly may be more inclined to try and accept novel foods because of diet-related attitudes and beliefs that are formulated throughout the years.

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