The increased international sharing of data in research consortia and the introduction of new technologies for sequencing challenge the informed consent (IC) process, adding complexities that require coordination between research centres worldwide. Rare disease consortia present special challenges since available data and samples may be very limited. Thus, it is especially relevant to ensure the best use of available resources but at the same time protect patients' right to integrity. To achieve this aim, there is an ethical duty to plan in advance the best possible consent procedure in order to address possible ethical and legal hurdles that could hamper research in the future. Therefore, it is especially important to identify key core elements (CEs) to be addressed in the IC documents for international collaborative research in two different situations: (1) new research collections (biobanks and registries) for which information documents can be created according to current guidelines and (2) established collections obtained without IC or with a previous consent that does not cover all CEs. We propose here a strategy to deal with consent in these situations. The principles have been applied and are in current practice within the RD-Connect consortia - a global research infrastructure funded by the European Commission Seventh Framework program but forward looking in terms of issues addressed. However, the principles established, the lessons learned and the implications for future research are of direct relevance to all internationally collaborative rare-disease projects.