Data confidentiality and data integrity
The process of sharing data can be direct from one researcher to another, or via externally available databases. These may be completely open access (such as the majority of those provided by EMBL-EBI), or may be accessible only to individuals who request access via Data Access Committee (DAC) or similar (for example EMBL-EBI's European Genome–Phenome archive or the Sanger Institute's Decipher).
Maintaining confidentiality and integrity
How much access to the data do you have the ability to give (based on your ethical approval and informed consent of your research participants)?
If complete anonymisation is possible, can you pseudonymise and maintain the link-key within your organisation only?
Its crucial to ensure that your research participants have given consent for sharing of non-anonymised data, and that anyone with whom you share the data knows their responsibilities in maintaining it.
Sharing within the EU is safeguarded by the EU Data Protection Directive. However, safe sharing outside of EU member states requires an understanding of how data is treated within those countries/territories.