title: The gustin (CA6) gene polymorphism, rs2274333 (A/G), is associated with fungiform papilla density, whereas PROP bitterness is mostly due to TAS2R38 in an ethnically-mixed population.
abstract: PROP responsiveness is associated with TAS2R38 haplotypes and fungiform papilla density. Recently, we showed that a polymorphism in the gene coding for the salivary trophic factor, gustin (CA6), affects PROP sensitivity by acting on cell growth and fungiform papillae maintenance, in a genetically homogeneous cohort. Since population homogeneity can lead to over estimation of gene effects, the primary aim of the present work was to confirm gustin's role in PROP bitterness intensity and fungiform papillae density in a genetically diverse population. Eighty subjects were genotyped for both genes by PCR techniques. PROP responsiveness was assessed by a filter paper method and fungiform papilla density was determined in each subject. As expected, PROP bitterness ratings were lower in individuals with the AVI/AVI diplotype of TAS2R38 than in individuals with PAV/PAV and PAV/AVI diplotypes. However, no differences in PROP bitterness among genotypes of the gustin gene, and no differences in the density of fungiform papillae related to TAS2R38 diplotype were found. In contrast, the density of fungiform papillae decreased as the number of minor (G) alleles at the gustin locus increased. In addition, the distribution of TAS2R38 genotypes within each gustin genotype group showed that the occurrence of recessive alleles at both loci was infrequent in the present sample compared to other populations. These findings confirm that papillae density is associated with gustin gene polymorphism, rs2274333 (A/G), in an ancestrally heterogeneous population, and suggest that variations in the frequency of allele combinations for these two genes could provide a salient explanation for discrepant findings for gustin gene effects across populations.
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Monserrato, CA 09042, Italy.
authors.forename: Iole Tomassini
authors.initials: IT
authors.lastname: Barbarossa
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Monserrato, CA 09042, Italy; Department of Food Science, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
authors.forename: Melania
authors.initials: M
authors.lastname: Melis
authors.affiliation: Department of Food Science, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
authors.forename: Mitchell Z
authors.initials: MZ
authors.lastname: Mattes
authors.affiliation: Department of Life and Environment Sciences, University of Cagliari, Monserrato, CA 09042, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Calò
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Monserrato, CA 09042, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Muroni
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Monserrato, CA 09042, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Crnjar
authors.affiliation: Department of Food Science, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA. Electronic address: tepper@aesop.rutgers.edu.
authors.forename: Beverly J
authors.initials: BJ
authors.lastname: Tepper
mesh_terms: D000293:Adolescent; D000328:Adult; D002256:Carbonic Anhydrases / Q000235:genetics*; D005787:Gene Frequency; D060005:Genotyping Techniques; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D011441:Propylthiouracil / Q000008:administration & dosage; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D013649:Taste / Q000235:genetics*; D055697:Taste Perception / Q000235:genetics*; D014059:Tongue / Q000033:anatomy & histology*; D055815:Young Adult; D000098706:Taste Receptors, Type 2
chemical_list: D043562:Receptors, G-Protein-Coupled; D000098706:Taste Receptors, Type 2; D011441:Propylthiouracil; D002256:Carbonic Anhydrases; C477051:carbonic anhydrase VI
keywords: Fungiform papillae; Genetically heterogeneous population; PROP tasting; TAS2R38; Trophic factor gustin (CA6) gene