Table 1

Frequency and disease risk of 5 classes of genotypes under the model.
Class	Susceptible homozygotes	Heterozygote of susceptible alleles	Heterozygote with one R and one S allele	Heterozygote of resistant alleles	Resistant homozygotes

Genotype	S_iS_i	S_iS_i, i ≠ j	R_iS_j	R_iR_j, i ≠ j	R_iR_i
Frequency	Θ	q²- Θ	2 pq	p²- Π	Π
Probability of Favorable Outcome	x	ax	bx	cx	dx

Notation: Frequency of allele S_iis q_i; frequency of allele R_iis p_i. p = p_i; q = q_i= 1 - p; ; . The subscripts of R alleles and the subscripts of the S alleles are unrelated.
Lipsitch et al. BMC Medical Genetics 2003 4:2 doi:10.1186/1471-2350-4-2