The Genetic Iceberg: Risk and Uncertainty

Abstract

New genetic technologies make it possible to screen populations in order to identify individuals’ risks or susceptibilities to specific medical conditions. On the basis of such population screening, otherwise healthy, symptomless people can be placed in the medically ambiguous position of being at risk. Equally, individuals may be tested on the basis of a family history that suggests a risk of an inherited condition. The identification of risk is probabilistic: it rests on the allocation of risk values. These are, in part, dependent on current understanding of the relationship between a given genetic make-up (the genotype) and its manifestation in physical characteristics or medical conditions (the phenotype). These are not always established with any degree of certainty and on the basis of genetic testing and family history, individuals may be identified as having high, moderate or low risks, and more specific values attached in percentage terms. Indeed, levels of risk assessment can appear to be arbitrary and moveable depending on how clinics choose to set the boundaries between, say, ‘high’ and ‘moderate’ risks. In some clinical contexts, such allocations to categories of risk are contingent upon organizational decisions and constraints concerning the allocation of resources.