title: Quinine Bitterness and Grapefruit Liking Associate with Allelic Variants in TAS2R31.
abstract: Multiple psychophysical gene-association studies suggest a single nucleotide polymorphism (SNP) within the bitter receptor gene TAS2R19 on chromosome 12 may be functional. Previously, the Arg299Cys SNP (rs10772420) has been associated with differential bitterness of quinine and differential liking for grapefruit juice. However, quinine does not activate TAS2R19 in vitro; likewise, limonin and naringin, bitter compounds in grapefruit, do not activate TAS2R19 in vitro. Here, we examined quinine bitterness (whole-mouth swish-and-spit stimuli and regionally delivered quinine across 4 loci) and remembered liking for grapefruit juice to test whether they associate with SNPs in another nearby gene, TASR2R31. We observed SNP-phenotype associations between whole-mouth quinine bitterness and self-reported liking for grapefruit juice with SNPs in TAS2R31, and regional quinine bitterness followed a similar trend, but did not reach significance. Present data provide independent replication of prior associations reported for TAS2R19. However, we also observed strong linkage disequilibrium (LD) between TAS2R19 and TAS2R31 SNPs. When present data are considered in light of existing functional expression data, this suggests phenotypic associations reported previously for rs10772420 may potentially be due to LD between this SNP and polymorphism(s) in, or closer to, TAS2R31. If confirmed, this would reduce the number of TAS2Rs with putatively functional polymorphisms to 5.
authors.affiliation: Sensory Evaluation Center, Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA, jeh40@psu.edu.
authors.forename: John E
authors.initials: JE
authors.lastname: Hayes
authors.affiliation: Sensory Evaluation Center, Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Emma L
authors.initials: EL
authors.lastname: Feeney
authors.affiliation: Sensory Evaluation Center, Department of Food Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Alissa A
authors.initials: AA
authors.lastname: Nolden
authors.affiliation: Providence Veterans Affairs Medical Center, Providence, RI 02908, USA, Division of Behavior Genetics, Rhode Island Hospital and Center for Alcohol and Addiction Studies, Brown University, Providence, RI 02912, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: McGeary
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D032083:Citrus paradisi / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D056726:Genetic Association Studies; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D011601:Psychophysics; D011803:Quinine / Q000494:pharmacology*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D055697:Taste Perception / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult; D000098706:Taste Receptors, Type 2
chemical_list: D043562:Receptors, G-Protein-Coupled; D000098706:Taste Receptors, Type 2; D011803:Quinine
keywords: Project GIANT-CS; bitter receptors; bitterness; direct scaling; false positive; linkage disequilibrium (LD); psychophysics; taste