Question

Hi
Could anyone please provide me the principle needed to use single nucleotide polymorphisms to predict bitter tasting ability.

Answer 1

Genetic variation in taste perception can be characterized in terms of single nucleotide polymorphisms (SNPs) in taste receptor genes. Taste receptor function for sweet, fat, and bitter tastes forms much of the basis for the known inter-individual differences in taste perception.

The fat taste receptor cluster determinant 36 (CD36), the sweet taste receptor type 1 member 2 (T1R2) and sweet taste receptor type 1 member 3 (T1R3), and the bitter taste receptor T2R38 contain common polymorphisms that may alter taste perception, food preference, and food selection.

The rs1761667 single nucleotide polymorphism (SNP) in the CD36 gene has been linked to fat taste sensitivity, the rs35874116 SNP in the TAS1R2 gene has been related to sweet taste preference, and the rs713598 SNP in the TAS2R38 gene has been associated with aversion to bitter, green leafy vegetables.

Consuming bitter compounds generally results in food rejection, an evolutionary adaptation to avoid toxic substances such as rancid fat, hydrolyzed protein and plant alkaloids. Sensitivity to bitterness may lead to the avoidance of Brassica vegetables rich in fiber, thereby potentially being replaced with the consumption of energy-dense foods rich in sugar.

Kim et al. (2003) showed that the bitter receptor T2R38 mediated the sensitivity to PTC, a thiol compound chemically related to those found in green, leafy vegetables. Three common SNPs in the TAS2R38 gene result in amino acid substitutions at residues P49A (rs713598), A262V (rs1726866) and V296I (rs10246939). The C allele of the rs713598 SNP is associated with the PAV haplotype while the G allele is associated with the AVI haplotype. Individuals carrying two copies of the PAV haplotype typically have a strong aversion to the bitterness of PTC. Those who seldom taste PTC carry two copies of the AVI haplotype while heterozygotes (PAV/AVI) typically have an intermediate taste phenotype.