Evolution of phenylthiocarbamide taster trait in Mysore, South India

Background: The ability to taste phenylthiocarbamide (PTC), a bitter chemical has long been known to be a heritable trait, which is being widely used for both genetic and anthropological studies. The frequency of taster and non-taster allele is found to vary in different populations.
Aims and Objective: To investigate the frequency of taster trait in Mysore, South India.
Materials and Methods: The present investigation was conducted in Mysore, South India during 2002 - 2003. About 3282 subjects irrespective of age, sex, religion, food habits, socio-economic status were randomly selected from various parts of the city and a total of 180 families, which included Christian (50), Hindu (61) and Muslim (69) were screened from different localities of the city. Harris and Kalmus method was used to assess the PTC taster and nontaster phenotype.
Results: It was found that tasters were significantly more frequent than nontasters in all the four categories. The incidence of tasters was more in unbiased category (85%) and less in Muslim category (58%). Investigations on PTC tasting in the families of three different religious groups revealed that the tasters were significantly more frequent than nontasters. It was also found that heterozygous father or mother for the taster genes with nontaster partner had taster and nontaster progenies in the ratio 1.0: 1.54 indicating the deviation in the segregation pattern of test cross.
Conclusion: In Mysore, tasters are more frequent than nontasters. Variation in the frequency of nontaster allele in the religious groups could be due to inbreeding.

Keywords
Inbreeding, Mysore families, nontaster allele, phenylthiocarbamide taster trait