gene frequency

The proportion of an allele in a population compared with other alleles of that gene. Thus if a gene A has two alleles, a and A, and the frequency of a = 0.2 (20%) then the frequency of A must be 0.8 (80%) since A + a = 1 (100%). Although the term 'gene frequency' is commonly used by population geneticists, it would be more consistent with standard definitions of the word 'gene' to use the term 'allele frequency'. See also Hardy-Weinberg law.