In the February 21 Science Kim et al. report the isolation of a human gene that accounts for sensitivity to the taste of phenylthiocarbamide (PTC) (Science 2003, 299:1228-1231). Genome-wide linkage analysis of the trait identified a region on chromosome 7q that contains over a hundred genes. Analysis of linkage disequilibrium and single-nucleotide polymorphisms (SNPs) narrowed the search down to a 30 kilobase interval containing only a new TAS2R bitter taste receptor gene. Three common SNPs within the coding region of the TAS2R gene generate five haplotypes and these can account for the bimodal distribution of PTC taste sensitivity worldwide.