Risk functions for the CRisch, Odds and Probit models using parameters relevant to human complex genetic diseases. (a-f) Risk or probability (g
) of disease for an individual with x out of 2n risk alleles where the number of risk loci, n = 1,000 and the frequency of each risk allele, p = 0.3. The black dotted lines represent the proportion of individuals in the population who have x or more risk alleles. The parameters n, p, heritability on the underlying liability scale, , and disease prevalence, K, determine the relative risk of a single locus, τ. The legend lists the resulting broad sense heritability on the risk scale, (H2 in the legend). The shape of the risk functions is achieved with other combinations of n and p for the same K and .