Adult Polycystic Kidney Disease and insurance: A case study in genetic heterogeneity

Adult Polycystic Kidney Disease (APKD) is a single-gene autosomal dominant genetic disorder leading to end-stage renal disease (ESRD, meaning kidney failure). It is associated with mutations in either of two genes, APKD1 and APKD2, and although diagnosis is still mostly by ultrasonography rather than DNA-based tests, this may change in the future. Recent studies have shown that the rates of onset of ESRD associated with APKD1 mutations are much greater than those associated with APKD2 mutations, a form of genetic heterogeneity that differs from, for example, familial breast cancer. In this paper we model the the impact of mutations in APKD1 or APKD2 on critical illness insurance, extending the work of Gutierrez and Macdonald (2003), which was based on studies predating DNA-based tests. We then extend the model to life insurance and show that the financial impact is strongly dependent on the availability of treatment (dialysis and transplant), but that if it is available, extra premiums for life insurance are modest. We show that genetic heterogeneity introduces a novel problem, because carrying an APKD2 mutation is less risky than having a family history of APKD. Thus, in jurisdictions where family history may be used in underwriting but genetic tests may not, it may be illegal to use knowledge that benefits the applicant.