The genotypic and allelic frequencies were obtained by direct counting, and the differences in frequencies among the populations were evaluated using chi-square test with Yates’ correction[13]using Graphpad software (San Diego, CA;http://www.graphpad.com/quickcalcs/contingency1. cfm). A value ofP< 0.05 andPc< 0.05 was considered sig- nificant. The Hardy–Weinberg equilibrium[14]was tested by calculating the expected genotype frequencies and comparing them to the observed values.