Coding single nucleotide polymorphisms and haplotype diversity of human bitter taste receptor genes in the Korean population

Bitter taste is crucial for the survival of organisms because it helps to avoid the ingestion of potentially harmful substances mostly found in plants. It is mediated by the bitter taste receptors that reside on the surface of the taste cells in the tongue. Genetic variations of these receptors have shown different responses to bitter taste compounds and the frequencies of these variations were different within and between populations. In this study, we investigated the diversity and frequencies of functional variants of human bitter taste receptor (hTAS2R) genes by direct sequencing of 25 hTAS2R genes in Koreans. A total of 59 cSNPs with an average of two cSNPs per gene were identified and ∼ 80% of cSNPs are nonsynonymous substitutions resulting in amino acid replacement. Also, 85 different haplotypes ranging from 2 to 18 haplotypes in each gene were identified in this study. One or two haplotypes of each hTAS2R gene were generally common, but the repertoire of haplotypes was different from other populations since different cSNPs were observed in the Koreans. The results of this study were similar to those of other populations supporting the fact that human bitter taste receptor genes have more genetic variation within and between populations than do most other genes. The repertoire and frequencies of cSNPs and haplotypes in the hTAS2R genes will provide information to identify a functional receptor for a ligand which is common in our environment.