Predicted curves for disease incidence (/100,000/year) of a population experiencing transmission distortion as a function of allele frequency, where for homozygote AA the penetrance is λ
= 500 and λ
= 0 (high differences in penetrances). Four models of gene expression were explored ('A' dominant to 'a' (---), alleles codominant (-- --), allele effects multiplicative (-- ··· --), and 'A' recessive to 'a' (·········)). The penetrance for heterozygous genotype is always between (or equal to) those of homozygotes.