phenylthiourea and Dysgeusia

It is unknown what causes uraemic symptoms in renal disease. Chronic kidney disease (CKD) patients are known to have increased levels of urea, sodium, potassium and phosphate in their saliva compared with those without renal disease. The present cross-sectional study investigated associations between known genetic traits of taste and self-reported upper gastrointestinal (GI) symptoms experienced in CKD patients with the changes in saliva composition found in renal failure.. Fifty-six CKD patients (35 males, 21 females, age 67±14 years), with stages 4 and 5 renal failure, selected from a tertiary hospital renal outpatient clinic participated in this study. Subjects answered a questionnaire to assess upper GI symptoms and tested for the genetic taste recognition thresholds of thiourea, phenylthiocarbamide and sodium benzoate. Saliva samples were collected to determine biochemical composition. Possible associations between genetic taste variations, saliva composition and upper GI symptoms were investigated.. Of the 56 patients enroled, 29 (52%) reported major upper GI uraemic symptoms, whereas 27 (48%) had no symptoms or only minor complaints of dry mouth. There was a strong association between the symptomatic burden a patient experienced and the genetic ability to taste thiourea (P<0.0003). Uraemic symptoms of taste changes (P<0.004) and nausea (P<0.002) were found to be related to a patient's genetic ability to taste thiourea.. This study provides evidence that the genetic ability to taste thiourea as bitter, in combination with the increase in active compounds found in CKD patient's saliva, impacts on the uraemic upper GI symptoms experienced.

Topics: Aged; Aged, 80 and over; Cross-Sectional Studies; Dysgeusia; Female; Gastroenteritis; Genetic Predisposition to Disease; Humans; Kidney Failure, Chronic; Male; Middle Aged; Nausea; Phenylthiourea; Saliva; Self Report; Severity of Illness Index; Sodium Benzoate; Taste Threshold; Thiourea; Uremia; Xerostomia

Pine mouth, also known as pine nut syndrome, is an uncommon dysgeusia that generally begins 12 to 48 hours after consuming pine nuts. It is characterized by a bitter metallic taste, usually amplified by the consumption of other foods, which lasts 2 to 4 weeks. Recent findings have correlated this disorder with the consumption of nuts of the species Pinus armandii, but no potential triggers or common underlying medical causes have been identified in individuals affected by this syndrome. We report a 23-year-old patient affected by pine mouth who also underwent a phenylthiocarbamide taste test and was found to be a taster for this compound. TAS2R38 genotyping demonstrated that this subject was a homozygous carrier of the proline-alanine-valine taster haplotype. We, therefore, hypothesize that homozygous phenylthiocarbamide taster status may be a potential contributor for pine mouth events. Although based on a single observation, this research suggests a connection between genetically determined bitter taste perception and the occurrence of pine nut dysgeusia events.

Topics: Adult; Dysgeusia; Female; Genotype; Homozygote; Humans; Nuts; Phenylthiourea; Pinus; Syndrome; Taste; Young Adult

One of the critical factors that determines individual differences in dietary behavior and nutritional status is the sensory-affecting quality of food, in particular its taste. Variation of one bitter taste receptor gene, TAS2R38, which is associated with the differential sensitivity to phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), has been demonstrated to affect the dietary intake pattern. A case study was performed to examine the association of the TAS2R38 genotypes/haplotypes with the body size (height, weight and BMI) and with the food and nutrient intake. Eighty-four college students, all females, with an age range of 18-21 y were recruited from the University of Shizuoka. The genotypes of two common single nucleotide polymorphisms in TAS2R38 (A49P and I296V) were determined by PCR-restriction fragment length polymorphism (RFLP) method. The height, weight and body mass index (BMI), and (in a subgroup of 47 subjects) food and nutrition intake estimated from 3 d of food recording, were compared between homozygotes for the PTC/PROP-nontaster haplotype (AI haplotype) and carriers with the PTC/PROP-taster haplotype (PV haplotype). The results show that the homozygotes with AI haplotype were taller and heavier than the carriers of PV haplotype, while BMI values were similar between them. The former group also had higher energy and carbohydrate intakes than the latter group. Neither vegetable nor dairy product intake was different between the homozygotes with AI haplotype and the carriers of PV haplotype. In conclusion, the PTC/PROP-nontaster TAS2R38 genotype/haplotype was associated with height and weight but not with BMI, which may in turn have influenced the energy and carbohydrate intakes.

Topics: Adolescent; Adult; Body Height; Body Mass Index; Body Weight; Diet; Dietary Carbohydrates; Dysgeusia; Eating; Energy Intake; Female; Genotype; Humans; Phenylthiourea; Polymorphism, Single Nucleotide; Propylthiouracil; Students; Taste; Universities; Young Adult

This study sought to replicate recent findings that both patients and relatives are significantly more likely to be phenylthiocarbamide (PTC) nontasters than healthy controls, and that within the patient group, nontasters have more severe positive and/or negative symptoms than tasters. Associations between PTC-tasting status and olfactory identification scores also were examined.. PTC perception and olfactory identification were assessed in 48 patients with schizophrenia or schizoaffective disorder, 28 first-degree relatives, and 32 healthy volunteers.. The three groups did not differ in PTC taste sensitivity. Findings did not change after: a sensitivity analysis that re-categorized participants who "possibly" tasted PTC, excluding Caucasian participants, or restricting the sample of patients to only those with schizophrenia. Among the patients, tasters and nontasters did not differ with regard to positive, negative, or general psychopathology symptoms. In the combined sample and the three groups separately, there were no associations between PTC-tasting status and olfactory identification scores.. This study, conducted specifically as an attempt to replicate previously reported findings, failed to provide support for PTC perception as an endophenotypic marker for schizophrenia. Further research is warranted.

Topics: Adult; Control Groups; Diagnostic and Statistical Manual of Mental Disorders; Dysgeusia; Family; Female; Genetic Markers; Humans; Male; Phenotype; Phenylthiourea; Psychiatric Status Rating Scales; Schizophrenia; Schizophrenic Psychology; Taste Threshold