Health- and disease-related events may be of highly significance for patients and their relatives. Naming a medical diagnosis is one of them. It carries the inherent power of (re)configuring the individuals' life courses, which are moreover closely linked to those of their relatives, and especially blood families in the case of (hereditary) genetic diseases. Drawing on ethnographic observations and narratives from patients and relatives involved in some Belgian organizations concerned with genetic disorders, this paper is interested in the ways these concerned people make sense of the naming of a medical diagnosis event by (re)interpreting their past familial stories, trying to intervene in the present, and designing a desired future. Then, it explores the case of the annual charity TV show "Téléthon", which is an initiative launched at the initiative of some French-speaking patients’ organizations (POs) concerned with neuromuscular disorders in the aims at putting awareness on rare disorders and raising funds in order to support biomedical research, especially in the field of medical genetics. The point is to question the dynamic relationships between the individual and familial experiences and such collective mobilizations, that is to say the dynamic relationships between individual and collective dimensions of POs' evidence-based activism. The argument is that such forms of activism participate in the co-construction of "gene worlds" (Timmermans & Shostak, 2015), through the relations between various actors and institutions: POs, scientific and medical professionals, public health institutions, and healthcare systems.