PTC-Tasting ability in populations living in Kirghizia with special reference to hypersensitivity: Its relation to sex and age

Abstract

The dimorphism in sensitivity to PTC, with a dilution scale up to 29, was studied in 320 male and 320 female Kirghiz students, 45 male and 200 female Russian students in Frunze, and in 734 Kirghiz schoolchildren in a high-altitude area of South Kirghizia. Gene t frequency was 0.44 for the Kirghiz students, 0.56 for the Russian students, and 0.54 for the Kirghiz schoolchildren. In all the groups studied it was established that such factors as sex and age have no modifying effect on sensitivity to PTC and the pattern of the distribution of sensitivity. In all the groups the frequency of 'tasters' exceeded that of 'nontasters.' Among the Kirghiz students there was a very small percentage (1.2%) of hypersensitive subjects (dil. No. 18), while 14.1% of the Kirghiz children of one Kyzyl-Dzhar school were hypersensitive. Genealogical studies showed that all the hypersensitive subjects belonged to one small stock and lived in the same village. Family studies of probands suggest the existence of a new (third) allele (T2) which determines hypersensitivity to PTC.

Psychophysical Dissection of Genotype Effects on Human Bitter Perception

“…However, there are haplotypes that are associated with intermediate phenotypes and it is also accurate to say that taste perception of PTC (and PROP) is on a continuum. Studies conducted by anthropologists on populations around the world prior to the discovery of the molecular basis of PTC genetics suggest that some people can detect it at very low concentrations (Ibraimov and Mirrakhimov 1979) and given what we now know, a supersensitive haplotype may exist. Overall, the choice of whether to consider this taste trait as a qualitative or quantitative one is probably a practical issue and depends on why the trait is measured and the scientific questions being addressed.…”

The genetics of phenylthiocarbamide perception

“…Although the inability to taste PTC, or PTC taste blindness, has often been cited as a classical textbook example of a Mendelian trait, there are controversies surrounding its exact mode of inheritance. Incomplete dominance (Falconer 1946-47, Martin 1975, Jones and McLachlan 1991, Bartoshuk et al 1994, Reed et al 1995, multiple alleles (Rychkov and Borodina 1969, Rychkov and Borodina 1973, Ibraimov and Mirrakhimov 1979 and multigenic inheritance have all been suggested (Boyd and Boyd 1937, Boyd 1950, Babu et al 1984, Olson, Boehnke, Neiswanger et al 1989. Distributions of the rating of concentrated PROP solutions demonstrate bimodallity, but there is a broad range of intensity ratings within the taster group (figure 2).…”