This study focuses on cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a rare late-onset neurodegenerative disease of genetic origin. For CADASIL-and for other late-onset genetic conditions-genetic testing can predict whether an individual will develop the disease, even in the absence of symptoms. Multiple bodies of research in the social studies of medicine and in science and technology examine how individuals with genetic risks and diseases live through the in-between situation of being simultaneously healthy and on the cusp of ill-health. Drawing on data from interviews with 30 individuals concerned with CADASIL, we show that they do not allow themselves to be reduced to their genetic status. On the contrary, they appropriate the possibilities offered by biomedical knowledge and technology (genetic testing and reproductive technologies) to, as much as possible, control the way the disease manifests in their lives. We explore three pivotal moments or situations in the lives of these individuals: facing the possibility of genetic testing, dealing with the disease and its surveillance after the diagnosis, and becoming a parent with or without the assistance of reproductive technologies. In contrast to criticisms of geneticization, we examine how, at each of these stages, these individuals develop "tactics"-in the sense employed by de Certeau (1990)-with respect to genetics to keep the disease at arm's length and live as good a life as possible.