title: Age modifies the genotype-phenotype relationship for the bitter receptor TAS2R38.
abstract: BACKGROUND
  The purpose of this study was to investigate the effect of TAS2R38 haplotypes and age on human bitter taste perception.
  
  
  RESULTS
  Children (3 to 10 yrs), adolescents (11 to 19 yrs) and adults (mostly mothers, 20 to 55 yrs (N = 980) were measured for bitter taste thresholds for 6-n-propylthiouracil (PROP) and genotyped for three polymorphisms of the AS2R38 gene (A49P, V262A, I296V). Subjects were grouped by haplotype and age, as well as sex and race/ethnicity, and compared for PROP thresholds. Subjects with the same haplotype were similar in bitter threshold regardless of race/ethnicity (all ages) or sex (children and adolescents; all p-values > 0.05) but age was a modifier of the genotype-phenotype relationship. Specifically, AVI/PAV heterozygous children could perceive a bitter taste at lower PROP concentrations than could heterozygous adults, with the thresholds of heterozygous adolescents being intermediate (p < 0.001). Similar age effects were not observed for subjects with the PAV/PAV or AVI/AVI homozygous haplotypes (p > 0.05) perhaps because there is less variation in taste perception among these homozygotes.
  
  
  CONCLUSIONS
  These data imply that the change in PROP bitter sensitivity which occurs over the lifespan (from bitter sensitive to less so) is more common in people with a particular haplotype combination, i.e., AVI/PAV heterozygotes.
authors.affiliation: Monell Chemical Senses Center, 3500 Market St, Philadelphia, PA 19104, USA.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Mennella
authors.forename: M Yanina
authors.initials: MY
authors.lastname: Pepino
authors.forename: Fujiko F
authors.initials: FF
authors.lastname: Duke
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Reed
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D005006:Ethnicity / Q000235:genetics; D005260:Female; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D012737:Sex Factors; D013652:Taste Threshold / Q000235:genetics*; D000098706:Taste Receptors, Type 2
chemical_list: D043562:Receptors, G-Protein-Coupled; D000098706:Taste Receptors, Type 2