TAS2R38 rs1726867: Bitter Taste Perception Explained
The rs1726867 single nucleotide polymorphism is a missense variation in the TAS2R38 gene on chromosome 7 that causes a valine-to-alanine amino acid substitution. It serves as the central polymorphic site defining the classic human bitter taste perception haplotypes, widely known as AVI and PAV. Together with adjacent markers, this variant strongly influences how intensely an individual perceives bitter thiourea compounds found in cruciferous vegetables.
What each genotype means
High bitter sensitivity
You carry two copies of the C allele at rs1726867, which corresponds to the Ala262 variant and is strongly linked with the functional PAV taster haplotype. People with this genotype generally perceive bitter thiourea compounds, such as phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), as intensely bitter. This can statistically influence dietary preferences, such as lower liking or intake of bitter cruciferous vegetables and certain bitter alcoholic beverages, though real-world dietary patterns depend heavily on culture and learned habits.
Found in approximately 25% to 35% of people of European descent and roughly 50% or more in many East Asian populations where the taster allele is more prevalent.
Intermediate bitter sensitivity
You carry one taster allele (C) and one non-taster allele (T), reflecting heterozygous taste receptor sensitivity typically associated with a PAV/AVI diplotype. Individuals with this genotype typically display an intermediate sensitivity threshold to bitter thiourea compounds like PTC and PROP. While you are likely able to perceive bitterness in these substances, the intensity is generally lower than in homozygous tasters, and dietary associations remain modest and variable across studies.
Carried by approximately 45% to 50% of people globally, representing the most common genotype in European and American cohorts.
Low bitter sensitivity
You carry two copies of the T allele at rs1726867, corresponding to the Val262 variant tightly linked to the non-taster AVI haplotype. People with this genotype generally cannot perceive or have a very high detection threshold for bitter thiourea compounds such as PTC and PROP. Research observes that non-tasters may show higher tolerance for bitter foods like brassica vegetables, coffee, or dark beer, although actual nutrient intake and health outcomes are multifaceted and weakly correlated with this single trait marker alone.
Found in about 20% to 25% of individuals of European ancestry, but occurs at significantly lower frequencies in East Asian populations.
Molecular Profile and the AVI/PAV Haplotype
The single nucleotide polymorphism rs1726867 (also referenced historically in literature as c.785C>T) is located within the coding exon of the taste 2 receptor member 38 gene (TAS2R38). At the protein level, this alteration results in a missense substitution between alanine and valine at codon position 262 (Ala262Val). Rather than acting strictly in isolation, rs1726867 is inherited in high linkage disequilibrium alongside two companion missense variants: rs713598 (Pro49Ala) and rs10246939 (Val296Ile). Together, these three coding loci constitute the classic haplotypes termed PAV (Proline-Alanine-Valine) and AVI (Alanine-Valine-Isoleucine). Because rs1726867 provides the middle letter in this three-letter nomenclature, the C allele corresponds to alanine at residue 262 within the 'taster' PAV configuration, whereas the T allele codes for valine in the non-functional 'non-taster' AVI configuration. Structural biological studies demonstrate that variations at positions 49 and 262 alter the conformational receptor dynamics required for G-protein-coupled receptor activation upon binding bitter ligands.
Biological Function of the TAS2R38 Receptor
The TAS2R38 gene encodes a seven-transmembrane G-protein-coupled receptor localized primarily in the microvilli of type II taste bud cells on the human tongue and palate. It is exquisitely tuned to recognize compounds containing a thiourea (N-C=S) chemical moiety. Classic experimental ligands include synthetic probes like phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), as well as naturally occurring glucosinolates and isothiocyanates present in brassica vegetables such as broccoli, Brussels sprouts, kale, and watercress. When an agonist docks to a functional TAS2R38 receptor, intracellular calcium cascades trigger neurotransmitter release that sends bitter sensation signals via cranial nerves to the gustatory cortex. Beyond oral perception, researchers have identified TAS2R38 expression extra-orally, notably in the ciliated epithelial cells of the human respiratory tract, where receptor engagement triggers localized nitric oxide release and innate antimicrobial responses.
Phenotypic Associations and Evidence Strength
Evidence evaluating rs1726867 in bitter taste threshold sensitivity is robust, confirmed across decades of psychophysical, genetic, and epidemiological studies cataloged in PubMed and the GWAS Catalog. Individuals harboring functional PAV haplotypes (carrying the C allele at rs1726867) detect bitter thioureas at micromolar concentrations, whereas individuals homozygous for the AVI configuration (TT genotype at rs1726867) are largely insensitive to these compounds at equivalent levels. Beyond sensory testing, scientists have investigated downstream behavioral and health associations, including dietary preferences, vegetable intake frequency, alcohol consumption habits, and chronic rhinosinusitis susceptibility. However, evidence connecting rs1726867 directly to long-term health outcomes, diet quality, or metabolic risk remains limited and heterogeneous. Lifestyle choices, cultural culinary practices, childhood exposures, and compensation by other taste receptor families significantly buffer any single genetic effect.
Interpreting Your Genetic Results
Learning your rs1726867 genotype offers an educational glimpse into how sensory genetics shape day-to-day perception, but it is not a clinical diagnosis or medical predictor. Possessing a non-taster genotype does not prevent you from enjoying a healthy, vegetable-rich diet, nor does having a taster genotype condemn you to disliking nutrient-dense cruciferous produce. Many sensory taster traits can be moderated by culinary preparation techniques such as roasting, caramelization, seasoning with salt, or pairing with fats, all of which attenuate bitter notes. Furthermore, TAS2R38 variants should never be used to guide prescription medications, dietary supplement plans, or clinical treatments. Any questions regarding medical nutrition therapy, digestive symptoms, or airway health should be discussed directly with a qualified healthcare provider or registered dietitian.
How common is this variant?
The minor allele frequency for rs1726867 is approximately 0.44 globally, with heterozygous and homozygous states well balanced across most world populations. Frequencies remain relatively balanced across continental ancestries due to ancestral balancing selection, although specific rare non-AVI/PAV recombinant haplotypes occur at modest frequencies in African and Indigenous American populations.
Frequently asked questions
Does my rs1726867 genotype mean I am a supertaster?
Not necessarily. While carrying the C allele (linked to the PAV haplotype) makes you a sensitive taster of specific thiourea compounds, true clinical 'supertasters' also have higher anatomical densities of fungiform papillae on their tongue. TAS2R38 governs sensitivity to specific bitter chemicals rather than overall sensitivity to every taste modality.
Can rs1726867 explain why I dislike broccoli or Brussels sprouts?
It may be a contributing factor. Cruciferous vegetables contain natural glucosinolates that activate the functional receptor encoded by the PAV haplotype. However, culinary preparation methods, learned preferences, and other sensory genes also shape your personal enjoyment of these foods.
Are there health risks associated with the AVI non-taster genotype?
No direct disease risks are conclusively tied to this genotype alone. While researchers have studied links between TAS2R38 variants, respiratory immune defense, and sinus inflammation, current evidence is limited, and genotype is not a diagnostic marker for any illness.
Is this variant linked to medication reactions or pharmacology?
rs1726867 is not an established pharmacogenetic variant for drug dosing or toxicity. Synthetic compounds like propylthiouracil share the chemical structure tested in laboratories, but taste genotype does not dictate thyroid medication safety or metabolism.
Sources & further reading
Educational information only, last refreshed 9/10/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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