Both Taster and Non-taster Alleles Are Common

The alleles responsible for PTC taster and non-taster traits are common in populations worldwide.

Does this sound familiar?

You may remember from the sickle cell disease tutorial that balancing selection keeps two alleles of a gene at high frequency.

A pair of pie charts, one titled Africans and the other titled Non-Africans. The Africans pie chart has 4 sections, labeled P-A-V, A-V-I, A-A-I, and A-A-V, from largest to smallest. The Non-Africans pie chart has 3 sections, labeled P-A-V, A-V-I, and A-A-I, from largest to smallest. — Tasters and non-tasters in Africans and non-Africans. PAV=tasters; AVI= non-tasters; AAI/AAV=intermediate tasters