Under Hardy-Weinberg equilibrium, allele and genotype frequencies remain constant over generations.

• The allele frequencies are described by
  p + q = 1,
  where p is the dominant allele frequency and q is the recessive allele frequency.

• The genotype frequencies are described by
  p² + 2pq + q² = 1,
  where p² and q² are frequencies of the homozygous genotype and 2pq is the frequency of the heterozygous genotype.