Predictive medicine: new avenues of molecular genetics. For which benefit?

Predictive medicine may be defined as arriving at a definitive diagnosis th rough the study of genetic material in a healthy individual before the occu rrence of any symptom, while presumptive medicine is based on definitive di agnosis evidencing a factor that contributes to development of the disease but is not sufficient in itself for the disease to develop. In France, gene tic studies in individuals have recently been protected by bioethical laws requiring that sampling may not be conducted without prior obtention of the recipient's informed consent. The finding of genes responsible for disease s allows molecular diagnosis with limits which must not be overestimated. T he gene localized on a chromosome must be identified; gene sequencing has t o be done and the disease mutation(s) must be listed. Mutations affecting g enes are numerous and of various types. The benefit of predictive diagnosis depends on the possibilities of prevention or early treatment, the severit y of the future disease, the precocity of its appearance and the degree of certainty of the prediction. Before being applied to the recipient, the fea sibility of various predictions or pre-symptomatic diagnosis must be carefu lly analyzed in each family. The finding of specific treatments always occu rs in a delayed manner, leading to an unsatisfactory situation in which dia gnostic means are not accompanied by treatment. Decision making in predicti ve medicine is therefore ethically very difficult.