%0 Journal Article
%T Age modifies the genotype-phenotype relationship for the bitter receptor TAS2R38
%A Julie A Mennella
%A M Yanina Pepino
%A Fujiko F Duke
%A Danielle R Reed
%J BMC Genetics
%D 2010
%I BioMed Central
%R 10.1186/1471-2156-11-60
%X 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.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.The experience of bitterness occurs after certain chemicals contact taste receptors located in cells on the surface of the tongue. Some investigators hypothesize that this sense provides information so that people do not ingest bitter-tasting toxic chemicals [1]. Potent poisons are found in many plants (e.g., like ricin and castor beans) which render them inedible [2]. However for many other plants, the potency or amount of toxin is low enough so that even though some (e.g., turnips or cabbage) might taste bitter, they can be eaten with fewer consequences [3]. However this poison detection system is not perfect because not everyone perceives the intensity of a fixed bitter stimulus in the same way [4,5]. The classic example of individual differences in taste sensitiv
%U http://www.biomedcentral.com/1471-2156/11/60