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Gustin Gene Polymorphism and 6-n-propylthiouracil (PROP) Taste (gustinprop)

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ClinicalTrials.gov Identifier: NCT01097915
Recruitment Status : Completed
First Posted : April 2, 2010
Results First Posted : December 21, 2016
Last Update Posted : December 21, 2018
Sponsor:
Information provided by (Responsible Party):
Iole Tomassini Barbarossa, University of Cagliari

Study Type Observational
Study Design Observational Model: Cohort;   Time Perspective: Prospective
Condition Dysgeusia
Enrollment 170
Recruitment Details  
Pre-assignment Details  
Arm/Group Title Super Tasters Medium Tasters Non Tasters
Hide Arm/Group Description Subjects highly sensitive to PROP Subjects sensitive to PROP Subjects no sensitive to PROP
Period Title: Overall Study
Started 50 70 50
Completed 27 28 20
Not Completed 23 42 30
Arm/Group Title Super Tasters Medium Tasters Non Tasters Total
Hide Arm/Group Description Subjects highly sensitive to PROP Subjects sensitive to PROP Subjects no sensitive to PROP Total of all reporting groups
Overall Number of Baseline Participants 50 70 50 170
Hide Baseline Analysis Population Description
Caucasian and were originally from Sardinia, Italy. Participants between 20-30 years were eligible for the study.
Age, Categorical  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 50 participants 70 participants 50 participants 170 participants
<=18 years
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Between 18 and 65 years
50
 100.0%
70
 100.0%
50
 100.0%
170
 100.0%
>=65 years
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Age, Continuous  
Mean (Standard Deviation)
Unit of measure:  Years
Number Analyzed 50 participants 70 participants 50 participants 170 participants
25  (7) 25  (8) 25  (6) 25  (7)
Sex: Female, Male  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 50 participants 70 participants 50 participants 170 participants
Female
35
  70.0%
40
  57.1%
34
  68.0%
109
  64.1%
Male
15
  30.0%
30
  42.9%
16
  32.0%
61
  35.9%
Race (NIH/OMB)  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 50 participants 70 participants 50 participants 170 participants
American Indian or Alaska Native
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Asian
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Native Hawaiian or Other Pacific Islander
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Black or African American
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
White
50
 100.0%
70
 100.0%
50
 100.0%
170
 100.0%
More than one race
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Unknown or Not Reported
0
   0.0%
0
   0.0%
0
   0.0%
0
   0.0%
Region of Enrollment  
Measure Type: Number
Unit of measure:  Participants
Italy Number Analyzed 50 participants 70 participants 50 participants 170 participants
50 70 50 170
healthy volunteers  
Measure Type: Number
Unit of measure:  Participants
Number Analyzed 50 participants 70 participants 50 participants 170 participants
50 70 50 170
1.Primary Outcome
Title Association Between Gustin Gene Polymorphism and PROP Sensitivity
Hide Description

We examine associations between PROP status and the polymorphism rs2274333 (A/G) of the gene that codify for the salivary protein, gustin/CA6, Which has been suggested as a trophic factor that promotes growth and development of taste buds by acting on taste bud stem cells.

The intensity of taste perception evoked by PROP and NaCl solutions was estimated to evaluate PROP taster status and molecular analysis of the gustin gene polymorphism was performed in individuals classified by PROP status using PCR techniques.

Time Frame 7 months
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Super Tasters Medium Tasters Non Tasters
Hide Arm/Group Description:
Subjects highly sensitive to PROP
Subjects sensitive to PROP
Subjects no sensitive to PROP
Overall Number of Participants Analyzed 27 28 20
Measure Type: Number
Unit of Measure: percentage of participants
Genotype AA 85.19 50.99 25.00
Genotype AG 14.81 35.71 20
Genotype GG 0 14.29 55
Allele A 92.59 67.86 35
Allele G 7.40 32.14 65
Show Statistical Analysis 1 Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Super Tasters, Medium Tasters, Non Tasters
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value <0.01
Comments [Not Specified]
Method Fisher Exact
Comments [Not Specified]
2.Secondary Outcome
Title Association Between PROP Sensitivity and Saliva Zinc Ion Concentration
Hide Description Since the enzymatic function of gustin (CA6) depends upon the presence of Zn at its active site we measured the salivary zinc ion concentration in subjects classified as super-taster, medium taster and non-taster.The salivary Zn2+ concentration was measured with a QuantiChromTM zinc Assay kit (Gentaur, Brussels, Belgium) where the color intensity is directly proportional to the Zn2+ concentration in the sample.
Time Frame 7 months
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Super-tasters Medium Tasters Non-tasters
Hide Arm/Group Description:
Subjects highly sensitive to PROP
Subjects sensitive to PROP
Subjects no sensitive to PROP
Overall Number of Participants Analyzed 27 28 20
Mean (Standard Error)
Unit of Measure: microg/dl
57.3  (13) 89.5  (17.2) 149.64  (26.4)
Show Statistical Analysis 1 Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Super-tasters, Medium Tasters, Non-tasters
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value <0.004
Comments [Not Specified]
Method ANOVA
Comments [Not Specified]
3.Secondary Outcome
Title Association Between PROP Sensitivity and BMI
Hide Description Since individual ability to taste PROP may be correlated with BMI, we determined BMI (kg/m^2) in subjects classified as super-taster, medium taster and non-taster.Weight (kg) and height (m) were recorded for each subject.
Time Frame 7 months
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Super-tasters Medium Tasters Non-tasters
Hide Arm/Group Description:
Subjects highly sensitive to PROP
Subjects sensitive to PROP
Subjects no sensitive to PROP
Overall Number of Participants Analyzed 27 28 20
Mean (Standard Error)
Unit of Measure: Kg/m^2
20.3  (0.48) 20.76  (0.58) 22.58  (0.84)
Show Statistical Analysis 1 Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Super-tasters, Medium Tasters, Non-tasters
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value <0.048
Comments [Not Specified]
Method ANCOVA
Comments the three factors of the Stunkard and Messick Questionnaire were considered as covariates.
4.Secondary Outcome
Title Electrophysiological Recordings From the Tongue for the Objective Evaluation of Individual Variations of 6-n-propylthiouracil (PROP) Sensitivity
Hide Description electrophysiological recordings from the tongue of 43 subjects classified for their taste sensitivity to 6-n- propyltiouracil (PROP) and genotyped for the specific receptor gene, TAS2R38. Density of fungiform papillae was also determined in each subject. The biopotentials were recorded by means of differential electrophysiological derivations between two silver electrodes, one in contact with the ventral surface of the tongue and one in perfect adhesion with the dorsal surface.
Time Frame 1 year
Hide Outcome Measure Data
Hide Analysis Population Description
Relationship between depolarization amplitude of signals and PROP taster status.
Arm/Group Title Super-Taster Medium Taster Non Taster
Hide Arm/Group Description:
Subjects highly sensitive to PROP
Subjects sentitive to PROP
Subjects no sensitive to PROP
Overall Number of Participants Analyzed 15 15 13
Mean (Standard Error)
Unit of Measure: mV
97,08867  (6,538191) 75,42000  (6,538191) 48,48231  (7,023144)
Show Statistical Analysis 1 Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Super-Taster, Medium Taster, Non Taster
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value < 0.00001
Comments [Not Specified]
Method ANOVA
Comments [Not Specified]
5.Secondary Outcome
Title Association Between PROP Sensitivity and Fungiform Papilla Density
Hide Description 43 subjects were classified for their taste sensitivity to 6-n- propyltiouracil (PROP) and density of fungiform papillae was determined in each subject.
Time Frame 6 months
Hide Outcome Measure Data
Hide Analysis Population Description
Relationship between density of fungiform papillae and PROP taster status.
Arm/Group Title Super-tasters Medium Tasters Non-tasters
Hide Arm/Group Description:
Subjects highly sensitive to PROP
Subjects sensitive to PROP
Subjects no sensitive to PROP
Overall Number of Participants Analyzed 15 15 13
Mean (Standard Error)
Unit of Measure: No./cm2
51.66  (5.25) 33.49  (5.26) 18.53  (7.023)
Show Statistical Analysis 1 Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Super-tasters, Medium Tasters, Non-tasters
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value < 0.00001
Comments [Not Specified]
Method ANOVA
Comments [Not Specified]
6.Secondary Outcome
Title Taste Perception of Sweet, Sour, Salty, Bitter and Umami and Changes Due to L-Arginine Supplementation, as a Functin of Genetic Ability to Taste PROP.
Hide Description Taste perception was assessed by testing the ability to recognize, and the responsiveness to, representative solutions of the five taste qualities, also when supplemented with L-Arg, in subjects classified as PROP-tasters.
Time Frame 8 months
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Primary Taste Quality Primary Taste Quality Supplemented With L-Arg
Hide Arm/Group Description:
we taste Sucrose, NaCl, Citric Acid, Caffeine and MSG
we taste Sucrose, NaCl, Citric Acid, Caffeine and MSG, each supplemented with L-Arginine (1:1)
Overall Number of Participants Analyzed 64 64
Measure Type: Count of Participants
Unit of Measure: Participants
sucrose Undet Threshold
18
  28.1%
2
   3.1%
Correct identification
40
  62.5%
20
  31.3%
Incorrect teste response
6
   9.4%
42
  65.6%
NaCl Undet Threshold
1
   1.6%
1
   1.6%
Correct identification
52
  81.3%
41
  64.1%
Incorrect teste response
11
  17.2%
22
  34.4%
Citric Acid Undet Threshold
5
   7.8%
4
   6.3%
Correct identification
49
  76.6%
47
  73.4%
Incorrect teste response
10
  15.6%
13
  20.3%
caffeine Undet Threshold
6
   9.4%
6
   9.4%
Correct identification
56
  87.5%
56
  87.5%
Incorrect teste response
2
   3.1%
2
   3.1%
MSG Undet Threshold
7
  10.9%
0
   0.0%
Correct identification
26
  40.6%
33
  51.6%
Incorrect teste response
31
  48.4%
31
  48.4%
Show Statistical Analysis 1 Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Primary Taste Quality, Primary Taste Quality Supplemented With L-Arg
Comments [Not Specified]
Type of Statistical Test Superiority or Other
Comments [Not Specified]
Statistical Test of Hypothesis P-Value < 0.00001
Comments [Not Specified]
Method Chi-squared
Comments [Not Specified]
Time Frame 7 months
Adverse Event Reporting Description [Not Specified]
 
Arm/Group Title Super Tasters Medium Tasters Non Tasters
Hide Arm/Group Description Subjects highly sensitive to PROP Subjects sensitive to PROP Subjects no sensitive to PROP
All-Cause Mortality
Super Tasters Medium Tasters Non Tasters
Affected / at Risk (%) Affected / at Risk (%) Affected / at Risk (%)
Total   --/--   --/--   --/-- 
Show Serious Adverse Events Hide Serious Adverse Events
Super Tasters Medium Tasters Non Tasters
Affected / at Risk (%) Affected / at Risk (%) Affected / at Risk (%)
Total   0/27 (0.00%)   0/28 (0.00%)   0/20 (0.00%) 
Show Other (Not Including Serious) Adverse Events Hide Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events 0%
Super Tasters Medium Tasters Non Tasters
Affected / at Risk (%) Affected / at Risk (%) Affected / at Risk (%)
Total   0/27 (0.00%)   0/28 (0.00%)   0/20 (0.00%) 
Certain Agreements
Principal Investigators are NOT employed by the organization sponsoring the study.
There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.
Results Point of Contact
Layout table for Results Point of Contact information
Name/Title: Iole Tomassini Barbarossa, Associate Professor
Organization: University of Cagliari
Phone: +390706754144
EMail: tomassin@unica.it
Layout table for additonal information
Responsible Party: Iole Tomassini Barbarossa, University of Cagliari
ClinicalTrials.gov Identifier: NCT01097915     History of Changes
Other Study ID Numbers: UNICADBSITB-1
First Submitted: April 1, 2010
First Posted: April 2, 2010
Results First Submitted: July 19, 2016
Results First Posted: December 21, 2016
Last Update Posted: December 21, 2018