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Molecular variants associated with flavor perceptions and ancestral proportions of Ecuadorian populations

Published:September 23, 2019DOI:https://doi.org/10.1016/j.fsigss.2019.09.024

      Abstract

      The perception of taste is determined by several factors, including genetics, which at the same time is related with the diet and diseases in different populations. We aimed to identify the frequency of six single nucleotide polymorphisms (rs307355, rs35744813, rs713598, rs1726866, rs10246939 and rs11091046) involved in the perception of sweet, bitter and salty flavor in Ecuadorian mestizo population. It was found that the presence of the T allele of rs307355 and rs35744813 is associated with decreased ability of subjects to carry out specific discrimination of sweetness, this is particularly interesting given the correlation found (p = 0.0022) between sucrose perception and family history of cancer and diabetes. Furthermore, rs713598, rs1726866 and rs10246939 do not influence the ability to perceive the bitter taste. Concerning the perception of the salty taste, rs11091046 does influence the capacity of detecting it more easily. This theoretical knowledge of the genetic influence on taste perception can contribute to the understanding of eating habits and their impact on human health.

      Keywords

      1. Introduction

      The taste sensation is produced in receptor proteins that recognize ligands belonging to the five types of tastes: salty, sweet, sour, bitter and umami. Sweet taste receptors are neuroepithelial cells in the taste buds, arranged on the surface of the tongue [
      • Bachmanov A.A.
      • Bosak N.P.
      • Lin C.
      • et al.
      Genetics of taste receptors.
      ]. How sensitive a population is to certain flavors is reflected in their diet and the same time correlated to nutritional disorders such as overweight and obesity, representing a risk factor for diabetes, cardiovascular disease, cancer, premature death, etc. [
      • Garcia-Bailo B.
      • Toguri C.
      • Eny K.M.
      • et al.
      Genetic variation in taste and its influence on food selection.
      ]. Thus, the aim of this study was to evaluate the frequencies of certain polymorphisms which make us more or less sensitive to sweet, bitter, and salty flavors in Ecuadorian mestizo individuals (n = 110). The umami taste was already discussed in Paz-y-Miño et al. [
      • Paz-y-Miño C.
      • García-Cárdenas J.M.
      • López-Cortés A.
      • et al.
      Evaluation of ancestral membership proportions and genotype distribution in the perception of Umami taste in Ecuadorian mestizos.
      ].

      2. Materials and methods

      2.1 Participants and samples

      A total of 110 healthy Ecuadorian mestizo individuals between the ages of 17 and 62 were included in the study. Once the participants signed the informed consent, blood samples were collected as well as additional parameters such as age, sex, and clinical history.

      2.2 Threshold taste evaluation

      To determine the threshold taste of participants we conducted a test at different concentrations depicted on Table 1. The dilutions were classified from levels 1 to 5, being 1 undetectable, 2 weak, 3 moderate, 4 strong and 5 very strong.
      Table 1Threshold and taster types of each flavor.
      TasterFlavors Concentrations
      Bitter (Sodium benzoate)Salty (Sodium Chloride)Sweet (Sucrose)
      Undetectable0.0010.020.05
      Weak0.080.050.1
      Moderate0.250.10.4
      Strong0.40.50.5
      Very Strong0.7511

      2.3 Genotyping

      DNA was extracted from peripheral blood samples using the PureLinkT Genomic DNA Kit (Invitrogen, Carlsbad, CA) followed by DNA quantification using NanoDrop 2000 (ThermoScientific, Waltham, MA). Genotypes for the six SNPs (rs307355, rs35744813, rs713598, rs1726866, rs10246939 and rs11091046) were determined using PCR and sequencing by conditions detailed in Paz-y-Miño et al. [
      • Paz-y-Miño C.
      • García-Cárdenas J.M.
      • López-Cortés A.
      • et al.
      Evaluation of ancestral membership proportions and genotype distribution in the perception of Umami taste in Ecuadorian mestizos.
      ].

      2.4 Genetic ancestry determination

      The population was genotyped by multiplex reaction using 46 autosomal ancestry informative insertion deletion markers (AIM-INDELs) described by Pereira et al. [
      • Pereira R.
      • Phillips C.
      • Pinto N.
      • et al.
      Straightforward inference of ancestry and admixture proportions through ancestry-informative insertion deletion multiplexing.
      ]. Fluorescent DNA fragments were sequenced by capillary electrophoresis in the Genetic Analyzer ABI 3130 (Applied Biosystems, Austin, TX) and were identified using the software GeneMapper v3.1 (Life Technologies, Carlsbad, CA).

      2.5 Statistical analysis

      Descriptive statistical analysis was used. Allelic and genotypic frequencies of each SNP were used to calculate genotype information, and Hardy-Weinberg Equilibrium (HWE) was determined. To find statistically significant relationships between frequencies, the Fisher statistic exact test was applied (expected frequencies below 5).

      3. Results

      3.1 Participant´s demographics and characteristics

      Women composed 59.10% and men 40.90% of the group. The genotypes are shown in Table 2.
      Table 2Distribution and genotypic frequencies of polymorphic variants.
      GenesTastePolymorphismsAllelesn
      TAS1R3Sweetrs35744813C/C76
      C/T29
      T/T5
      rs307355C/C79
      C/T27
      T/T4
      TAS2R38Bitterrs713598C/C66
      C/G38
      G/G6
      rs1726866C/C69
      C/T36
      T/T5
      rs10246939G/G66
      G/A39
      A/A5
      AT2Saltyrs11091046C/C32
      C/A31
      A/A47

      3.2 Genetic ancestry determination

      The participants involved in this study were the same used in Paz-y-Miño et al. [
      • Paz-y-Miño C.
      • García-Cárdenas J.M.
      • López-Cortés A.
      • et al.
      Evaluation of ancestral membership proportions and genotype distribution in the perception of Umami taste in Ecuadorian mestizos.
      ].

      3.3 Sweet

      The polymorphism rs307355 has the lowest frequency and no statistical significance was found. However, rs35744813 was correlated (p < 0.001) with perception of sucrose at 1%. Furthermore, T allele of rs307355 and rs35744813 was associated with decreased ability of discrimination of sweetness [
      • Wasalathanthri S.
      • Hettiarachchi P.
      • Prathapan S.
      Sweet taste sensitivity in pre-diabetics, diabetics and normoglycemic controls: a comparative cross sectional study.
      ,
      • Yeomans M.R.
      • Tepper B.J.
      • Rietzschel J.
      • et al.
      Human hedonic responses to sweetness: role of taste genetics and anatomy.
      ]. In this study we found a between family medical records and their perception of sucrose (p = 0.022).

      3.4 Bitter

      The rs713598 rs1726866 rs10246939 did not influence the ability to perceive the bitter taste, however we found difference between women and men and their ability to detect bitterness in the lowest concentration (0.001%, p = 0.040), which was also related to alcohol consumption (p = 0.02).

      3.5 Salty

      Individuals with rs11091046 polymorphism required very strong concentrations of sodium chloride. Amongst the Ecuadorians, there was a statistical significance for the genotypes C/C at 0.5% (p < 0.05) and 1.0% (p < 0.05). This established the fact that the rs11091046 polymorphism influenced the ability to detect saltiness [
      • Zambrano A.K.
      • Gaviria A.
      • Cobos-Navarrete S.
      • et al.
      The three-hybrid genetic composition of an Ecuadorian population using AIMs-InDels compared with autosomes, mitochondrial DNA and Y chromosome data.
      ,
      • Li J.Z.
      • Absher D.M.
      • Tang H.
      • et al.
      Worldwide human relationships inferred from genome-wide patterns of variation.
      ].

      4. Discussion

      Different populations express different variants of TAS1R3, TAS2R38 and AT2 genes, giving their ethnicity. Ecuadorians is a three hybrid population with European (33%), African (13%) and Native American (51%) components [
      • Zambrano A.K.
      • Gaviria A.
      • Cobos-Navarrete S.
      • et al.
      The three-hybrid genetic composition of an Ecuadorian population using AIMs-InDels compared with autosomes, mitochondrial DNA and Y chromosome data.
      ]. These variants may come from these ancestral genetic components, increasing the variability of flavor sensibility among Ecuadorians.

      5. Conclusion

      This variation had dictated the sensitivity to perceive flavors in the food Ecuadorian mestizo population consume. These polymorphisms may influence a population’s food preferences, diet, nutritional status, personal habits, and health risks [
      • Paz-y-Miño C.
      • García-Cárdenas J.M.
      • López-Cortés A.
      • et al.
      Evaluation of ancestral membership proportions and genotype distribution in the perception of Umami taste in Ecuadorian mestizos.
      ,
      • Soualmia H.
      • Riadh J.
      • Feki M.
      • et al.
      Lack of association between C3123A polymorphism of the angiotensin II type 2 receptor gene and hypertension in Tunisian population.
      ].

      Funding

      None.

      Declaration of Competing Interest

      None.

      Acknowledgement

      None.

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