Trial Outcomes & Findings for Gustin Gene Polymorphism and 6-n-propylthiouracil (PROP) Taste (NCT NCT01097915)

Last Updated: 2018-12-21

Results Overview

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.

Recruitment status

COMPLETED

Target enrollment

170 participants

Primary outcome timeframe

7 months

Results posted on

2018-12-21

Participant Flow

Participant milestones

Participant milestones
Measure	Super Tasters Subjects highly sensitive to PROP	Medium Tasters Subjects sensitive to PROP	Non Tasters Subjects no sensitive to PROP
Overall Study STARTED	50	70	50
Overall Study COMPLETED	27	28	20
Overall Study NOT COMPLETED	23	42	30

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

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

Baseline characteristics by cohort

PRIMARY outcome

Timeframe: 7 months

Outcome measures

Outcome measures
Measure	Super Tasters n=27 Participants Subjects highly sensitive to PROP	Medium Tasters n=28 Participants Subjects sensitive to PROP	Non Tasters n=20 Participants Subjects no sensitive to PROP
Association Between Gustin Gene Polymorphism and PROP Sensitivity Genotype AA	85.19 percentage of participants	50.99 percentage of participants	25.00 percentage of participants
Association Between Gustin Gene Polymorphism and PROP Sensitivity Genotype AG	14.81 percentage of participants	35.71 percentage of participants	20 percentage of participants
Association Between Gustin Gene Polymorphism and PROP Sensitivity Genotype GG	0 percentage of participants	14.29 percentage of participants	55 percentage of participants
Association Between Gustin Gene Polymorphism and PROP Sensitivity Allele A	92.59 percentage of participants	67.86 percentage of participants	35 percentage of participants
Association Between Gustin Gene Polymorphism and PROP Sensitivity Allele G	7.40 percentage of participants	32.14 percentage of participants	65 percentage of participants

SECONDARY outcome

Timeframe: 7 months

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.

Outcome measures

Outcome measures
Measure	Super Tasters n=27 Participants Subjects highly sensitive to PROP	Medium Tasters n=28 Participants Subjects sensitive to PROP	Non Tasters n=20 Participants Subjects no sensitive to PROP
Association Between PROP Sensitivity and Saliva Zinc Ion Concentration	57.3 microg/dl Standard Error 13	89.5 microg/dl Standard Error 17.2	149.64 microg/dl Standard Error 26.4

SECONDARY outcome

Timeframe: 7 months

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.

Outcome measures

Outcome measures
Measure	Super Tasters n=27 Participants Subjects highly sensitive to PROP	Medium Tasters n=28 Participants Subjects sensitive to PROP	Non Tasters n=20 Participants Subjects no sensitive to PROP
Association Between PROP Sensitivity and BMI	20.3 Kg/m^2 Standard Error 0.48	20.76 Kg/m^2 Standard Error 0.58	22.58 Kg/m^2 Standard Error 0.84

SECONDARY outcome

Timeframe: 1 year

Population: Relationship between depolarization amplitude of signals and PROP taster status.

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.

Outcome measures

Outcome measures
Measure	Super Tasters n=15 Participants Subjects highly sensitive to PROP	Medium Tasters n=15 Participants Subjects sensitive to PROP	Non Tasters n=13 Participants Subjects no sensitive to PROP
Electrophysiological Recordings From the Tongue for the Objective Evaluation of Individual Variations of 6-n-propylthiouracil (PROP) Sensitivity	97,08867 mV Standard Error 6,538191	75,42000 mV Standard Error 6,538191	48,48231 mV Standard Error 7,023144

SECONDARY outcome

Timeframe: 6 months

Population: Relationship between density of fungiform papillae and PROP taster status.

43 subjects were classified for their taste sensitivity to 6-n- propyltiouracil (PROP) and density of fungiform papillae was determined in each subject.

Outcome measures

Outcome measures
Measure	Super Tasters n=15 Participants Subjects highly sensitive to PROP	Medium Tasters n=15 Participants Subjects sensitive to PROP	Non Tasters n=13 Participants Subjects no sensitive to PROP
Association Between PROP Sensitivity and Fungiform Papilla Density	51.66 No./cm2 Standard Error 5.25	33.49 No./cm2 Standard Error 5.26	18.53 No./cm2 Standard Error 7.023

SECONDARY outcome

Timeframe: 8 months

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.

Outcome measures

Outcome measures
Measure	Super Tasters n=64 Participants Subjects highly sensitive to PROP	Medium Tasters n=64 Participants Subjects sensitive to PROP	Non Tasters Subjects no sensitive to PROP
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. Citric Acid · Undet Threshold	5 Participants	4 Participants	—
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. Citric Acid · Correct identification	49 Participants	47 Participants	—
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. MSG · Correct identification	26 Participants	33 Participants	—
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. sucrose · Undet Threshold	18 Participants	2 Participants	—
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. sucrose · Correct identification	40 Participants	20 Participants	—
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. sucrose · Incorrect teste response	6 Participants	42 Participants	—
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. NaCl · Undet Threshold	1 Participants	1 Participants	—
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. NaCl · Correct identification	52 Participants	41 Participants	—
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. NaCl · Incorrect teste response	11 Participants	22 Participants	—
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. Citric Acid · Incorrect teste response	10 Participants	13 Participants	—
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. caffeine · Undet Threshold	6 Participants	6 Participants	—
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. caffeine · Correct identification	56 Participants	56 Participants	—
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. caffeine · Incorrect teste response	2 Participants	2 Participants	—
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. MSG · Undet Threshold	7 Participants	0 Participants	—
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. MSG · Incorrect teste response	31 Participants	31 Participants	—

Adverse Events

Super Tasters

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Medium Tasters

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Non Tasters

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Iole Tomassini Barbarossa, Associate Professor

University of Cagliari

Phone: +390706754144

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place

Measure	Super Tasters n=50 Participants Subjects highly sensitive to PROP	Medium Tasters n=70 Participants Subjects sensitive to PROP	Non Tasters n=50 Participants Subjects no sensitive to PROP	Total n=170 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Age, Categorical Between 18 and 65 years	50 Participants n=5 Participants	70 Participants n=7 Participants	50 Participants n=5 Participants	170 Participants n=4 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Age, Continuous	25 years STANDARD_DEVIATION 7 • n=5 Participants	25 years STANDARD_DEVIATION 8 • n=7 Participants	25 years STANDARD_DEVIATION 6 • n=5 Participants	25 years STANDARD_DEVIATION 7 • n=4 Participants
Sex: Female, Male Female	35 Participants n=5 Participants	40 Participants n=7 Participants	34 Participants n=5 Participants	109 Participants n=4 Participants
Sex: Female, Male Male	15 Participants n=5 Participants	30 Participants n=7 Participants	16 Participants n=5 Participants	61 Participants n=4 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Asian	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) White	50 Participants n=5 Participants	70 Participants n=7 Participants	50 Participants n=5 Participants	170 Participants n=4 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Region of Enrollment Italy	50 participants n=5 Participants	70 participants n=7 Participants	50 participants n=5 Participants	170 participants n=4 Participants
healthy volunteers	50 participants n=5 Participants	70 participants n=7 Participants	50 participants n=5 Participants	170 participants n=4 Participants