Primary immunodeficiencies (PIDs) have now become recognized as a worldwide health problem. Rapid development of immunological and genetic technologies has led to the discovery of more than 200 PIDs and more than 150 disease-related genes. Progress in the field is expected to take a new turn after the introduction of new-generation sequencing technologies that will enable searches for currently unknown PID-related genes. By contrast, even with progress in molecular genetics, many patients remain ill and die early because of the lack of diagnostic or treatment facilities, or both. Thus, the gap between the knowledge accumulated and the appropriate management of patients with PIDs in everyday clinical practice has widened, necessitating PID awareness, particularly in countries with poor socioeconomic conditions. The J Project, established as a physician education and research collaboration program in Eastern and Central Europe, demonstrates how professional responsibility and long-term joint efforts can make a beneficial difference for patients with inborn errors of immunity.