Next-generation sequencing is increasingly used in clinical practice for the diagnosis of Mendelian diseases. Because of the high likelihood of secondary findings associated with this technique, the process of informing patients is beset with new challenges. One of them is regarding the type of secondary findings that ought to be disclosed to patients. The aim of this research is to propose a practical implementation of the notion of actionability, a common criteria justifying the disclosure of secondary findings but whose interpretation varies greatly among professionals. We distinguish three types of actionability corresponding to (1) well-established medical actions, (2) patient-initiated health-related actions and (3) life-plan decisions. We argue that actionability depends on the characteristics of the mutation or gene and on the values of patients. In discussing the return of secondary findings, it is important that the physician tries to get an impression of the specific situation and values of patients. Regarding variants of uncertain clinical significance in actionable genes, we found that different understandings of autonomy lead to different conclusions and that, for some of them, it may be legitimate to refrain from returning uncertain information.