Highly Penetrant Genetic Disorders: An Atlas for Critical Illness Insurance

For estimates of critical illness (CI) insurance premiums in the presence of a known mutation leading to a genetic disorder, the key quantity is the penetrance, that is the probability q(x) that the disease has developed by age x. This function is often estimated in the genetics literature, though typically with large confidence intervals. In this paper we suggest that the main features of real penetrance functions can be represented reasonably well by simple one-parameter families of functions, which can be scaled to fit the age range and lifetime penetrance. This gives a simple, direct, pragmatic way to obtain quick estimates of CI premium rates from published penetrance estimates, and also some indicative bounds for such premium rates, which are useful since confidence intervals usually cannot be estimated. To aid this process, as a short-cut to the solution of Thiele's equations in a multiple-state model, we give extensive tables in another report (Macdonald & Yang, 2003).