The relative increase in frequency of causal variants in samples of cases compared to samples of randomly ascertained individuals.

aFrequency of variants within the population.The relative increase of causal variant frequency is shown for 5, 10, and 20 causal variants, each with equal population frequencies of 0.001, 0.002, and 0.005 and genotypic RR of either 2 or 5 under a multiplicative, dominant, additive, and recessive model. The calculations were carried out under the assumption that the causal variants reside on separate haplotypes.