A potential trigger for pine mouth: a case of a homozygous phenylthiocarbamide taster

Abstract

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.

Keywords: Dysgeusia; PTC; Pine nuts; TAS2R38; Taste disturbance.

Figure 1

The Labeled Magnitude Scale (LMS) used to evaluate PTC bitterness perception.

Figure 2

Single Nucleotide Polymorphisms (SNPs) identified at amino acid positions 49 (A), 262 (B) and 295 (C) of TAS2R38 gene. The sequence above the chromatogram indicates the reference sequence, the presence/absence of the SNP derived allele is indicated with an arrow.