Analysis of genetic polymorphism of bitter taste receptor TAS2R19 and its relationship with alcohol drinking and eating habits in Japanese subjects

Background and objectives: Five basic tastes are messages that tell us something about what we put into our mouth, so we can decide whether it should be ingested. Among them, the bitter taste sense is thought to have arisen to warn individuals against the ingestion of poisonous substances, many of which have a bitter taste. However, bitter substances are contained in favorite beverages such as tea and beer, etc., and have been widely consumed in usual human life. Bitter substances are perceived by various bitter taste receptors (TAS2Rs), and among them it is well understood that the TAS2R38 gene polymorphisms influence individual differences in bitterness sensitivity to phenylthiocarbamide or propylthiouracil. Some TAS2R has also been reported to be associated with disease defence system. On the other hand, As for the other bitter components in foods, such as naringin in grapefruit, previous studies suggest that TAS2R19 is associated with the relationship between grapefruit preference and genetic polymorphism of TAS2R19 in Western subjects, however, there have been very few reports regarding Japanese subjects, so the present study takes advantage of the Tohoku Medical Megabank Organization (ToMMo) database to investigate the relationship of those in the Japanese population. Methods: The samples used here were from the TMM CommCohort Study participants, all of whom gave their written consent. The same ToMMo individual genotype construct genome reference panel for the Japanese population (2KJPN=~2000 subjects) was used. So, we extracted the aggregated data from dietary habit by questionnaire, and also analyzed single nucleotide polymorphism (SNP) in TAS2R19. Then we further analyzed if any specific TAS2R19 polymorphism (the 299th amino acid is either cysteine (C) or arginine (R) and other biological data are associated with clinical BMI, smoking habit, alcohol drinking frequency, food preference related to bitterness. Results: After our detailed analyses, it was shown that the gene frequencies of C299C, R299C, and R299R were approximately 5%, 35%, and 59%, respectively in Japanese ToMMo population. Moreover, there was no significant relationship between the genetic polymorphism of TAS2R19 and clinical BMI, smoking habit, alcohol drinking frequency. Conclusions: TAS2R19 was not associated with lifestyle-related factors in the Japanese population.