Age structure and the distribution of rare genetic diseases.

Equilibrium frequencies of rare deleterious genes in an age-structured population have been studied by using mathematical models. In the models, variable age-of-onset and variable penetrance of a trait have been incorporated. Numerical analyses show that the equilibrium gene frequencies can be approximated extremely well to those in nonoverlapping generations, as Haldane [1927] claimed. This property of rare deleterious genes in an age-structured population is important because population dynamics of such genes in a finite population can be studied easily.