Mutations in the BRCA1/2 genes increase the risk of breast and ovarian cancer, leading to complex medical decisions (surveillance, risk-reducing surgery) and major psychological consequences. A support group for BRCA1/2 mutation carriers has been conducted at the CHUV since 2016 by a psychologist-psychotherapist, a genetic counselor, and a geneticist. This article presents the context and then develops some of the psychological issues raised by the participants, focusing in particular on the notions of risk, uncertainty, and guilt. The processes at work in the group, between identification and differentiation, allow for a valuable work of appropriation and subjectivation around the presence of this genetic mutation.