Undiagnosed rare diseases include diseases with a well-characterised phenotype, diseases with unknown molecular causes or due to non-genetic factors, and pathological condition that cannot be named. Several initiatives have been launched for healthcare of patients with undiagnosed rare diseases. A project for development of medical records with special reference to the HL7 standards is being carried out in Genoa (Italy), taking into account regional and national regulations. The project is based on the integration of functionality related to patient diagnostics, taking into account omic sciences for disease prevention and risk assessment. Considering the evolution of standards, the use of FHIR is being considered in order to increase the elasticity of the system also in view of foreseeable adoption of this standard by the Italian healthcare system.