Phenylthiocarbamide Sensitivity Research Articles

Taste and oral somatosensation: Role of PTC bitter sensitivity, gender, and age

Sensitivity to the bitterness of phenylthiocarbamide (PTC) is considered to be linked to general taste perception, which is higher in women, and exhibits a slight decrease with age. Additionally, PTC sensitivity may contribute to somatosensory perception of spiciness and astringency. However, controversial data have been reported. This study investigates the relation between PTC perception, age, and gender on taste and somatosensory sensitivity using the Seven-iTT. A total of 200 healthy participants were classified based on their PTC perception, and subjects underwent an extended version of Seven-iTT to identify and rate the intensity of twelve stimuli. Results indicated that individuals classified as Tasters (T) exhibited higher taste scores compared to Non-Tasters (NT) for PTC, with age serving as a significant factor (p ≤ 0.009). Women outperformed men only among NT (p = 0.019). Older T demonstrated higher taste sensitivity than NT, suggesting that PTC status might act as a protective factor of gustatory function in aging. While PTC taster status significantly affected the intensity of sweet, salty, and bitter sensations (p ≤ 0.032), it had minimal impact on the intensity of somatosensory sensations (capsaicin and tannins). The combined use of Seven-iTT and the investigation of PTC status show promise for applications in research and clinical practice, offering a comprehensive approach to understanding taste perception and its implications for diet, nutrition, and aging.

TAS2R38 bitter taste perception in the Koṅkaṇī Sārasvata Brahmin population.

The TAS2R38 gene carries markers for phenylthiocarbamide (PTC) sensitivity. Various studies have investigated the genotype-phenotype association pattern for bitter tasting ability and other factors in different populations. However, a paucity of such information for endogamous Indian populations is the reason behind this study. To study the association of phenylthiocarbamide (PTC) sensitivity with TAS2R38 gene variations in Koṅkaṇī Sārasvata Brahmin population. We studied the association of the alleles rs714598, rs1726866, rs10246939 with PTC sensitivity and other factors in the Koṅkaṇī Sārasvata Brahmin population. DNA was extracted from 114 individuals belonging to the Koṅkaṇī Sārasvata Brahmin community. The TAS2R38 gene was sequenced to find the genotype distribution pattern. The association between genotype and phenotype was checked using the Chi-Square test and multifactorial logistical regression. We observed a 58.8% frequency of the AVI haplotype, which is the most prevalent in European populations. A higher number of non-taster haplotypes and diplotypes were observed in Koṅkaṇī Sārasvata Brahmins, with the allele rs10246939 showing a significant association with PTC bitter taste sensitivity in both allelic (p = 8.6 × 10-4; Allele-G, OR = 3.57 [95% CI = 1.66-7.69]) and genotype-based (p = 6.9 × 10-4; genotype-AG, OR = 3.11 [95% CI = 0.73-13.20]; genotype-GG, OR = 40 [95% CI = 3.58-447.03]) tests. Our results are in line with earlier studies, which report an association between PTC sensitivity and the TAS2R38 gene in different populations. In the global context, Koṅkaṇī Sārasvata Brahmins, who are mostly distributed along the southwestern coast of India, show a PTC sensitivity pattern slightly similar to that of West Eurasian populations. Our findings suggest ancestry specific selection in TAS2R38 gene variations for taste sensitivity at global level.

Relationship between Skeletal Maturity, BMI Percentile and Dental Caries Experience among Taster and Non-taster Children

Introduction: Ability of an individual to taste phenylthiocarbamide (PTC) substance divides the population in tasters and non-tasters. The objective of this study was to investigate the relationship between the taste ability for PTC substance with BMI percentile, skeletal maturity and dental caries experience within taster and non-taster children of age 8-12 years.
 Hypotheses: Tasting ability for PTC affects the BMI percentile, skeletal maturity and dental caries experience and emerge as a useful caries risk assessment tool.
 Evaluation of Hypotheses (Materials and Method): One hundred children of 8-12 years were randomly selected and their taste perception was assessed using PTC sensitivity test. Radiovisiography (RVG) of middle phalanx was obtained to determine the skeletal maturity by using Rajgopal and Kansal modification 2005. Anthropometric measurements were recorded to obtain BMI value and then BMI percentile was calculated using CDC Pediatric growth charts. For dental caries assessment, deft/DMFT scores were recorded.
 Results: The non-tasters had early skeletal maturation, higher caries experience and higher BMI percentile than the tasters.
 Conclusion and Clinical Relevance: PTC Sensitivity is a genetically controlled trait showing strong association with dental caries. From the results of this study we can conclude that the genetic ability of tasting PTC affects the BMI percentile, skeletal maturity and dental caries experience. Thus it can emerge as a useful caries risk assessment tool helping in planning the preventive measures and interceptive orthodontics in children.

Perceived acceptability of partial enteral nutrition (PEN) using oral nutritional supplement drinks in adolescent and adult Crohn's disease outpatients: A feasibility study.

Studies, mainly in Japanese cohorts, have shown that partial enteral nutrition (PEN) including oral nutritional supplement (ONS) drinks can prolong disease remission and increase drug effectiveness in Crohn's disease (CD). Acceptability is a key feasibility parameter to determine whether PEN is a viable treatment option in UK CD patients. We report the results of a single centre cross-sectional feasibility study carried out to investigate perceived acceptability of PEN using ONS drinks and whether ONS preference varies with sex, nutritional status or phenylthiocarbamide (PTC) sensitivity. Patients with a confirmed CD diagnosis were recruited using convenience sampling from an adult and adolescent gastroenterology outpatient clinic over 3 years. Blind taste testing of 5 polymeric ONS drinks were conducted using a validated 9-point hedonic rating scale followed by completion of an acceptability questionnaire based on the preferred ONS drink. A subset of patients took home the preferred ONS drink for a 7-day ONS study. 105 CD patients (55 males), aged 34.9 (±15.4) years were recruited and 28 patients completed the 7-day ONS study. Overall impression scores did not significantly vary with nutritional status, sex, BMI, handgrip strength (HGS), mid-upper arm circumference (MUAC) or PTC sensitivity. Ensure plus milkshake™ rated highest for overall impression (6.5, p=<0.0001) and all other organoleptic properties (p<0.0001). The main perceived benefits of using ONS drinks as PEN related to assurance of nutrient intake (89%), convenience (86%), and improvement of gut symptoms (85%). The main perceived barriers related to reduction in pleasure from eating and drinking (56%), struggling with drink storage (54%) having less energy and feeling more tired than if eating 3 solid meals daily (52%). 65% of patients would consider using ONS drinks as PEN as a maintenance treatment option. 81% of patients felt confident-very confident about consuming ONS drinks daily as PEN for three months but this dropped to 64% and 37% at 6 and 12 months, respectively. There was a significant drop in perceived ease of use of ONS drinks as PEN after the 7-day ONS study (P=0.01). Use of ONS drinks as PEN have high perceived benefits and appear to be a feasible option for short-term use of 3-6 months in CD patients. However, confidence in long-term use of ONS drinks as PEN is low mainly due to the perceived social impact. Future studies should assess longer trial periods and volume of ONS drinks to increase the validity of these findings.

361 Methods for Identification and Classification of Phenylthiocarbamide Sensitivity in Mature Rams

Abstract Rams exhibit varying levels of sensitivity to phenylthiocarbamide (PTC), which has been correlated with the ability to perceive bitter-tasting foods. Previously, the only procedure for measuring PTC-sensitivity in rams involved a 9-d test phase with 5 PTC concentrations. The objective of this experiment was to develop a more streamlined approach for identifying and classifying rams on extreme ends of the bitter-tasting spectrum. Mature Targhee, Rambouillet, Polypay, and Composite-breed rams (n = 44), housed in three separate barns, and subjected to 4-d acclimation, 2-d sham, and 2-d testing phases. The 2-d sham phase was conducted to determine if ethanol-spiked water (delivery vehicle for PTC) influenced voluntary fluid intake; no effect (P = 0.16) was observed. The 2-d test phase was a side-by-side preference study between water (control; 3.0 kg) and 1 of 2 concentrations (0.2 and 2.0 mM) of PTC solution (3.0 kg) delivered on alternate days. Average consumption of PTC as a percentage of total test fluid intake was used determine taster status. No PTC-treatment effect (P ≥ 0.23) was observed, but within each treatment level, PTC intake was less (P &amp;lt; 0.001) than water intake. Classification levels of PTC consumption were determined by ± 1.0 standard deviation of the mean and used to classify rams into non- (n = 9; 61.5 ± 3.9%), intermediate- (n = 29; 40.7 ± 1.8%), or super- (n = 6; 15.6 ± 3.3%) PTC tasting groups, which were different (P &amp;lt; 0.001) from each other. Likewise, water consumption intakes were different (P&amp;lt; 0.001) between the non- (38.5 ± 3.9%), intermediate- (59.3 ± 1.8%), and super- (84.4 ± 3.3%) PTC tasting groups. The methods outlined in this study will facilitate further research focused on the influence of bitter tasting sensitivities on the dietary preferences of sheep.

Evolution of the bitter taste receptor TAS2R38 in colobines.

Bitter taste perception enables the detection of potentially toxic molecules and thus evokes avoidance behavior in vertebrates. It is mediated by bitter taste receptors, TAS2Rs. One of the best-studied TAS2R is TAS2R38. Phenylthiocarbamide (PTC) perception and TAS2R38 receptors vary across primate species, and this variation may be related to variation in dietary preferences. In particular, we previously found that the low sensitivity of TAS2R38s in Asian colobines likely evolved as an adaptation to their leaf-eating behavior. However, it remains unclear whether this low PTC sensitivity is a general characteristic of the subfamily Colobinae, a primate group that feeds predominantly on leaves. We performed genetic analyses, functional assays with mutant proteins, and behavioral analyses to evaluate the general characteristics of TAS2R38 in colobines. We found that PTC sensitivity is lower in TAS2R38s of African colobines than in TAS2R38s of omnivorous macaques. Furthermore, two amino acids shared between Asian and African colobines were responsible for low sensitivity to PTC, suggesting that the last common ancestor of extant colobines had this phenotype. We also detected amino acid differences between TAS2R38s in Asian and African colobines, indicating that they evolved independently after the separation of these groups.

PSIV-20 TAS2R genes in sheep and cattle compared to humans

Abstract The taste receptor gene family has been extensively studied in human and some genes have been linked to food preferences and addiction; however, research in foraging ruminants is limited. Identification of taste receptor genes in the sheep genome may provide insight regarding individual dietary range plant preferences. Bitter taste has been a large focus of research since Arthur Fox accidentally discovered the bitter tasting compound phenylthiocarbamide (PTC) and observed that bitter taste perception in humans is a variable trait. In theory, individuals who are sensitive to bitter taste will likely consume less bitter tasting foods, which are often antioxidant rich, and be more prone to disease and illness. The objective of this study was to examine known taste receptor genes in sheep and cattle and compare them with humans to determine similarities and differences. Type 2 taste receptors (T2R’s) are the only receptor of the taste gene family to perceive bitterness in foods. Using NCBI genome data viewer, the taste genes were identified on the human (GRCh38.p12), cattle (ARS-UCD1.2), and sheep (Oar_4.0; OORI1) genomes. All 3 species have one T2R gene cluster in common, which includes T2R genes 3, 4, 5, 38, 39, 40, 60, and 41. The span of this cluster is similar for humans (1,457,940 bp), sheep (1,541,593 bp), and cattle (1,594,610 bp). One gene in particular (T2R38) has been associated with PTC sensitivity and linked to aversion of some bitter tasting food in humans. Previous research on T2R38 identified 5 haplotypes, each expressing aversion to bitter taste differently. There is another T2R gene cluster which contains 10 annotated genes in sheep and cattle genomes; however, this region contains an additional 10 genes annotated in the human genome. Understanding genetic variation in TAS2R genes may translate to dietary preferences of sheep grazing on rangelands.

Bitter taste sensitivity, food intake, and risk of malignant cancer in the UK Women's Cohort Study.

There is variability in sensitivity to bitter tastes. Taste 2 Receptor (TAS2R)38 binds to bitter tastants including phenylthiocarbamide (PTC). Many foods with putative cancer preventive activity have bitter tastes. We examined the relationship between PTC sensitivity or TAS2R38 diplotype, food intake, and cancer risk in the UK Women's Cohort Study. PTC taste phenotype (n = 5500) and TAS238 diplotype (n = 750) were determined in a subset of the cohort. Food intake was determined using a 217-item food-frequency questionnaire. Cancer incidence was obtained from the National Health Service Central Register. Hazard ratios (HR) were estimated using multivariable Cox proportional hazard models. PTC tasters [HR 1.30, 95% confidence interval (CI) 1.04, 1.62], but not supertasters (HR 0.98, CI 0.76, 1.44), had increased cancer risk compared to nontasters. An interaction was found between phenotype and age for supertasters (p = 0.019) but not tasters (p = 0.54). Among women > 60years, tasters (HR 1.40, CI 1.03, 1.90) and supertasters (HR 1.58, CI 1.06, 2.36) had increased cancer risk compared to nontasters, but no such association was observed among women ≤ 60years (tasters HR 1.16, CI 0.84, 1.62; supertasters HR 0.54, CI 0.31, 0.94). We found no association between TAS2R38 diplotype and cancer risk. We observed no major differences in bitter fruit and vegetable intake. These results suggest that the relationship between PTC taster phenotype and cancer risk may be mediated by factors other than fruit and vegetable intake.

Complete Oral Nutritional Supplements: Dietitian Preferences and Clinical Practice

ABSTRACTOral nutritional supplements (ONS) are frequently prescribed for those at risk of malnutrition. Palatability is an important factor in long-term compliance. ONS selection is typically dietitian led, but the degree to which individual perceptions of palatability influence dietitian clinical decision making is unclear. This study aimed to explore factors that influence dietitians' ONS clinical practice, evaluate dietitian hedonic preferences and overall impression of specific ONS products, and study phenylthiocarbamide (PTC) sensitivity in relation to ONS hedonic ratings. Dietitians were recruited from six urban teaching hospitals. They completed a 10-item Clinical Practices Questionnaire prior to taste testing five samples of three ONS products. A 7-point hedonic Likert scale recorded ONS palatability ratings. A PTC test was conducted. Thirty-one dietitians were recruited. Nutritional value, patient palatability, patient acceptability, tolerance and hospital contracts were the factors identified as most likely to influence ONS prescription. All ONS were consistently highly rated for overall impression. The high-protein ONS was most highly rated for all hedonic characteristics. Taste was the highest rated hedonic characteristic across all products. No statistically significant relationship was found between PTC sensitivity and ONS overall impression. The key drivers of ONS dietitian clinical practice were identified. ONS hedonic characteristics and overall impression were highly rated, which suggested this range of products had wide appeal for dietetic professionals. The taste and consistency of the ONS were rated better than other hedonic characteristics (appearance, smell, aftertaste).

THE PREVALENCE OF TAS2R38 GENE PHENOTYPES AMONG THE PATIENTS WITH SOME ENDOCRINE SYSTEM DISORDERS

PTC (phenylthiocarbamide) is one of the focuses of interest from the medical point of view since a number of associations of the taster/nontaster status of PTC sensitivity with various human diseases have been found. It is estimated that ability of sense of PTC bitterness coded by a single gene TAS2R38. The threshold at which people can taste phenylthiocarbamide (PTC) is bimodal, and some people are tasters while, others are nontasters. In recent years, it is actively conducted the studies of genetic markers in various endocrine disorders. Endocrine diseases, particularly thyroid gland prevalence statistics in Georgia is very high. The goal of our research was to study the phenotype of PTC sensitivity among the patients with some endocrine system disorders in the population of Ajara region of Georgia, particularly diabetes type II and different type of goiter (nodular, diffuse etc.) to reveal any correlation between them. A total of 319 individuals including 136 patients with endocrine system and 183 randomly chosen healthy individuals participated in this study. Obtained results shows, that there is an increased incidence of diffuse toxic goiter in individuals with recessive phenotype of TAS2R38 gene and who are unable to taste PTC bitterness. While, PTC sensibility phenotype inclined to develop nodular goiter. Thus PTC- Sensibility phenotype may be considered one of the genetic markers in the forms of Goiter.

The population structure of Ukraine in relation to the phenylthiocarbamide sensitivity

BackgroundThe taste sensitivity to phenylthiocarbamide (PTC) is one of the classical genetic markers in human studies. PTC is of great interest from the medical point of view since a number of associations of the taster status with human diseases have been found. The aim of our study was to evaluate the population structure of Ukraine in relation to PTC sensitivity. MethodsThe study involved 533 people (78 males and 455 females) aged from 16 to 25years. The PTC solution in the concentration of 0.13% was prepared according to the method of Harris and Kalmus. The participants of the study analyzed the taste of the filter paper impregnated with PTC. If the trial subjects tasted PTC as “bitter”, “very bitter”, “bitterish”, the phenotype was defined as a taster. If the trial subject did not taste PTC (“no taste”, “taste of paper”), he/she was referred to a non-taster. ResultsThe structure of the sample of the Ukrainian population studied in relation to the phenotypic and genotypic frequency associated with the phenylthiocarbamide sensitivity has been studied. It has been shown that in the population there are 22% of those who do not feel the taste of phenylthiocarbamide. Among males there are a few more non-tasters than among females, however, the differences are not significant. The frequency of the dominant and recessive allele of the phenylthiocarbamide sensitivity gene in the sample calculated on the basis of the Hardy–Weinberg equation is generally pT=0.55 and qt=0.45, respectively. ConclusionsFrequencies of alleles T and t obtained in the male and female population under research are very close to the frequencies of the same alleles in some populations of India. Data of this study supplement the currently available information in relation to the genetic structure of modern Ukrainian cities.

Phenylthiocarbamide taste sensitivity is associated with sinonasal symptoms in healthy adults.

The bitter taste receptor T2R38, expressed in the tongue and nasal epithelium, has been shown to trigger sinonasal innate immunity contributing to the prevention of gram-negative upper airway bacterial infections. Common polymorphisms of the T2R38 gene, correlating with bitter taste sensitivity to phenylthiocarbamide (PTC), have been linked to differences in sinonasal innate immune response, with specific genotypes significantly more common in medically recalcitrant chronic rhinosinusitis patients. The purpose of this study was to examine this association between T2R38 function and sinonasal infection or symptoms in a healthy population. A survey of the frequency of sinus infections, as well as other nasal symptoms such as colds, allergies, and overall nasal quality of life (nQOL), was administered to healthy adult participants. nQOL was measured using a 0 to 3 scale of worsening symptoms. A PTC compound taste strip was administered with T2R38 taste sensitivity classified as extremely, somewhat, or not sensitive. Among 217 participants (55% female, 70% Caucasian, 42% age 21 to 25 years), 30% did not detect bitterness (nontasters), 34% were moderate tasters, and 36% were "supertasters," experiencing a strong, unpalatable bitterness. Supertasters were associated with less frequent sinus infections (p = 0.04), and PTC sensitivity was predictive of nasal symptoms: Supertasters had the best nQOL scores, followed by moderate tasters and nontasters (means: 0.65, 0.81, 1.00, respectively; p = 0.014 for trend). There were no significant associations with other variables. This study provides evidence that T2R38 functionality in the tongue correlates with nasal symptoms in healthy individuals.

Phenylthiocarbamide (PTC) perception in ultra-high risk for psychosis participants who develop schizophrenia: Testing the evidence for an endophenotypic marker

Reports suggesting that schizophrenia participants are more likely to be phenylthiocarbamide (PTC) non-tasters when compared to controls have recently been controversial. If supported, a genetic-based phenotypic variation in PTC taster status is implicated, suggesting a greater illness risk for those participants with recessive alleles for the TAS2R38 receptor. Should PTC insensitivity be a schizophrenia endophenotype, then it would be expected in follow-up of ultra high-risk for psychosis participants who later develop schizophrenia (UHR-S). UHR-S was hypothesised to show reduced PTC sensitivity compared to those who were previously at risk, but did not transition (UHR-NP). PTC perception was assessed in 219 UHR participants at long-term follow-up, of whom 53 had transitioned to psychosis (UHR-P) during the follow-up period. Fifteen of the 219 participants were diagnosed with schizophrenia. Seventy-eight had a family history of psychotic disorder. No differences in PTC taster status were found in UHR participants based upon transition to psychosis status, schizophrenia diagnosis, or family history of schizophrenia. This report indicates that schizophrenia development among UHR participants is not associated with PTC tasting deficits and fails to support previous findings that inability to detect the bitter taste of PTC is a schizophrenia endophenotype.

Role of phenylthiocarbamide as a genetic marker in predicting the predisposition of disease traits in humans.

The main objective of this study is to find out the genetic variation and predisposition of overweight/obese, smoking/alcoholism and thyroid disease traits among tasters and non-tasters in Mysore population, South India. Bitter-taste perception for phenylthiocarbamide (PTC) is a classically variable trait both within and between human populations. Many studies have reported that in world population, approximately 30% of them are PTC non-tasters and 70% are tasters. This investigation was conducted during the year 2009-2010 involving a total 1352 study subjects and divided into three different groups, considering the age ranging from 13 to 50 years. Phenylthiocarbamide taste sensitivity was measured by administering a freshly prepared 0.025% of phenylthiocarbamide solution using the Harris and Kalmus method with a slight modification and the results were recorded. In the first group of 100 obese/overweight children, 28% are taster and 72% are non-taster and among 100 control group 67% are tasters and 43% are non-tasters. In second group, out of 1152 individuals 710 (61.63%) are tasters and 442 (38.37%) are non-tasters including both males and females. In the third group, out of each 100 thyroid patients and the control group, tasters are significantly more frequent (61.41%) than the non-tasters (38.58%) in the control group, but a higher proportion of non-tasters are recorded among individuals with thyroid problems (68%) compared to tasters (32%). There is a significant higher incidence of PTC tasters than non-tasters among general population in this study. As phenotypic variation in PTC sensitivity is genetic in origin, this may represent a surrogate risk factor for the development of multifactorial disease and disorders.

The Relationship between Single Nucleotide Polymorphisms of theCarbonic Anhydrase 6Gene andPhenylthiocarbamide Taste Sensitivity, Taste Disorder

Received December 12, 2011 Revised February 6, 2012 Accepted February 6, 2012 Address for correspondence Mi-Kyung Ye, MD Department of OtolaryngologyHead and Neck Surgery, College of Medicine, Catholic University of Daegu, 33 Duryugongwon-ro 17-gil, Nam-gu, Daegu 705-718, Korea Tel +82-53-650-4525 Fax +82-53-650-4533 E-mail miky@cu.ac.kr * These authors contributed equally to the work. Background and ObjectivesZZThe phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) taste sensitivity varies among individuals. Recently, it is reported that PROP taste responsiveness is associated with carbonic anhydrase 6 (CA6) gene polymorphism. The CA6 gene, a zinc metalloprotein in human saliva, is affected in taste function and might be correlated with gustatory diversity. The aim of this study was to examine whether PTC taste sensitivity and taste disorder is associated with the CA6 gene polymorphism rs2274327 (C/T), rs2274328 (A/C), and rs2274333 (A/G). Subjects and MethodZZA total of 217 healthy normal subjects were recruited as controls, and 50 taste disorder patients were recruited as experimental group. The polymorphisms of CA6 gene were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis. All statistical analyses were calculated using the statistical package for the social science software. Haplotypes were estimated by Haploveiw and the PHASE programs. ResultsZZThe CA6 gene polymorphisms showed association with taste disorder but not with PTC sensitivity (taster/nontaster). The number of control subjects carrying AA genotype of single nucleotide polymorphism rs2274328 (A/C) in the CA6 gene was higher than the number of the subjects with taste disorder (p=0.048). However, there was no association between controls and taste disorder subjects in the haplotype analysis. ConclusionZZThese data suggest that the CA6 gene polymorphism rs2274328 could affect taste function impairment in patients with taste disorder. This observation requires a further functional study of gustin protein to clarify the association of the CA6 gene polymorphisms with the taste disorder and sensitivity. Korean J Otorhinolaryngol-Head Neck Surg 2012;55:155-60

ASSOCIATION OF PHENYLTHIOCARBAMIDE TASTE BLINDNESS TRAIT WITH EARLY ONSET OF CHILDHOOD OBESITY IN MYSORE

Ability to taste Phenylthiocarbamide (PTC) a bitter compound is widely used to know the heritable trait in both genetic and anthropological studies. The study is based on the ability of a person to sense the taste of PTC. Inability to taste has also been associated with medical illness not typically with taste impairment, so far no study has yet proved whether PTC blindness correlates with childhood obesity. This study is the first attempt to examine PTC sensitivity in obese children and healthy children to determine variation in the perception of bitter tastes which is associated with eating behavior, body mass index, and childhood obesity. The present investigation is carried out in Mysore, during years 2008 - 2009. Phenylthiocarbamide taste sensitivity was measured by administering PTC solution for obese and control children by modified method of Harris and Kalmus. The result focused that tasters were significantly more frequent (67%) than nontasters (33%) in control population. A higher proportion of non-tasters were observed in obese children (72%) when compare to non-obese subjects (28%). These differences were not explained by alterations in perception of basic taste sensitivity or age. Increased frequency of non-taster allele is evident in children with obese condition. This could be due to lack of preference for food among non-tasters. As the phenotypic variation in PTC sensitivity is genetic in origin, it may represent a surrogate risk factor for the development of childhood obesity.

Evolution of Functionally Diverse Alleles Associated with PTC Bitter Taste Sensitivity in Africa

Although human bitter taste perception is hypothesized to be a dietary adaptation, little is known about genetic signatures of selection and patterns of bitter taste perception variability in ethnically diverse populations with different diets, particularly from Africa. To better understand the genetic basis and evolutionary history of bitter taste sensitivity, we sequenced a 2,975 bp region encompassing TAS2R38, a bitter taste receptor gene, in 611 Africans from 57 populations in West Central and East Africa with diverse subsistence patterns, as well as in a comparative sample of 132 non-Africans. We also examined the association between genetic variability at this locus and threshold levels of phenylthiocarbamide (PTC) bitterness in 463 Africans from the above populations to determine how variation influences bitter taste perception. Here, we report striking patterns of variation at TAS2R38, including a significant excess of novel rare nonsynonymous polymorphisms that recently arose only in Africa, high frequencies of haplotypes in Africa associated with intermediate bitter taste sensitivity, a remarkably similar frequency of common haplotypes across genetically and culturally distinct Africans, and an ancient coalescence time of common variation in global populations. Additionally, several of the rare nonsynonymous substitutions significantly modified levels of PTC bitter taste sensitivity in diverse Africans. While ancient balancing selection likely maintained common haplotype variation across global populations, we suggest that recent selection pressures may have also resulted in the unusually high level of rare nonsynonymous variants in Africa, implying a complex model of selection at the TAS2R38 locus in African populations. Furthermore, the distribution of common haplotypes in Africa is not correlated with diet, raising the possibility that common variation may be under selection due to their role in nondietary biological processes. In addition, our data indicate that novel rare mutations contribute to the phenotypic variance of PTC sensitivity, illustrating the influence of rare variation on a common trait, as well as the relatively recent evolution of functionally diverse alleles at this locus.

Study of gustatory sensitivity to phenylthiocarbamide in thyroid diseases

The aim of the study was to reveal a relationship between gustatory sensitivity to phenylthiocarbamide (PTC) and thyroid disease. The distribution of PTC sensitivity was studied in 198 healthy individuals, 100 patients with autoimmune thyroiditis (AIT), 139 patients with nodular euthyroid goiter, and 100 patients operated on for thyroid cancer. There was a statistically significant decrease in the number of PTC-resistant male and females patients in the thyroid cancer group and an increase in the proportion of PTC-resistant male patients in the AIT and nodular euthyroid goiter groups.

Are Dietary Preferences Linked To Genes?

When many choices are available, humans chose foods that ‘taste good’. The concept of good taste for most people encompasses both flavor and texture of food. Although we acknowledge the universality of the goodness (sweet) or badness (bitter) of basic taste qualities, we also find that people differ, sometimes extremely so, in their ability to perceive these qualities. There is great variability in dietary habits both within and between various cultures. The interindividual differences in the quantity and quality of foods we chose to consume appear to be partially genetic and partially acquired or imposed by social or economic influences [1]. The contribution of genetics to dietary behaviors has been derived from family studies. The heritability estimates for macronutrients, including total energy intake range anywhere from 10 to 70% [2–6]. The different analytical and dietary assessment methods may explain the wide range of these estimates. These studies support the role of genetics in food consumption, but also point to the complexity of human dietary behaviors. With the exception of monogenetic conditions such as with leptin deficiency, no single gene is likely to have a great impact on food selection and intake. It is most likely that multiple physiological pathways are involved in these processes with those involved in taste perception being one of the actively studied subjects in the context of dietary behavior. Five modalities of taste can be detected by most mammals: sweet, salt, sour, bitter and umami [7–9]. Increasing evidence supports the addition of fat taste to the list of classical taste modalities. The exact role of each taste on dietary behavior is unclear, however, it is generally thought that sweet, salt and umami ensure nutrient acquisition while bitter and sour elicit food rejection. In the case of the bitter taste sensitivity, this may have served in ancestral times as a defense against ingestion of toxic compounds in foods. However, for modern humans, the role of bitter taste perception for the avoidance of noxious food is less important, and it is thought that individual differences to bitter taste sensitivity may influence health outcomes through its effect on dietary behaviors. In this regard, sensitivity to phenylthiocarbamide (PTC) and its chemical relative, 6-n-propylthiouracil (PROP) has provided some insight into the role of bitter taste perception on preferences and consumption of bitter foods. The haplotypes of the taste receptor, type 2, member 38 (TAS2R38) gene accounts for most of the variability of PTC sensitivity. There have been a few studies that support the role of this gene with preferences to vegetables and alcohol consumption. However, the current evidence has yet to support a link between genetic variability at this taste candidate gene, habitual consumption of certain foods and health related outcomes. This is expected when considering the complexity of the large number of taste related genes as well as other pathways that modulate eating habits, such as those involved in the central control of energy intake including neuropeptides and monoamine systems (reviewed in [10]) and the more recent developments regarding fat intake preferences [11,12].

Phenylthiocarbamide (PTC) Perception in Parkinson Disease

To examine phenylthiocarbamide (PTC) sensitivity in Parkinson disease (PD) patients and healthy volunteers to determine whether taster status represented a simple vulnerability marker for PD. The inability to taste PTC has been associated with a number of medical illnesses not typically associated with taste impairment. Abnormalities in the function/expression of G protein-signaling pathways have been implicated in PTC perception and also in dopamine expression and regulation in PD. No study has yet probed whether PTC tasting is disrupted in PD. PTC sensitivity was assessed in a small sample of 36 male PD patients and 20 healthy male comparison subjects using a standardized psychophysical method. A higher proportion of nontasters were found in patients relative to healthy comparison subjects. These differences were not explained by alterations in perception of basic taste intensity or age. Among patients, nontasters and tasters of PTC did not differ with regard to duration of illness, age of onset, severity of motor symptoms, or overall illness severity. These data suggest an increase in the frequency of PTC nontaster status in PD. As phenotypic variation in PTC sensitivity is genetic in origin, this may represent a surrogate risk factor for the development of PD.