Dictionary of Human Evolution and Biology

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PTC Taster/nontaster Polymorphism

Benign autosomal polymorphism characterized by an ability to taste or not taste phenylthiocarbamide, a stereolog of many goitrogens, all of which have a bitter taste to tasters. The taster ability is polymorphic in humans. PTC is in fact a more complex trait than a simple autosomal recessive as generally presented; it is likely a two-locus trait with incomplete penetrance at one locus that maps to chromosome

5. In 2003, a major gene in the system was mapped by positional cloning to a location in the bitter taste receptor gene family on human chromosome 7q, and was subsequently renamed PTC. This classic pedagogical polymorphism has been tested in hundreds of populations; in general, urban populations tend to have higher frequencies of the nontaster allele than populations recently removed from a gathering/hunting mode of subsistence. Aka taste blindness.

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