A system and method are presented for managing and using (e.g. for commercial or medical use) of a database. A verified database of a plurality of identified individuals is provided. The verified database comprises a plurality of individual-identifier data sets (IDSs) and relationship data. The verified database is processed in accordance with one or more parameters or conditions selected in accordance with at least one medical application, and a sub-group database is created including data records of the individuals from the verified database having said one or more selected parameters or conditions. This allows collection of data comprising the one or more selected parameters or conditions and delivery of at least part of the collected data to one or more users, and enables applying data from the verified database to provide personalized medicine service to at least one of the identified individuals.