International Registry of Clinical and Laboratory Parameters for Primary Immunodeficiencies of the European Society for Immunodeficiencies (ESID)

Primary immunodeficiencies (PID) are congenital disorders of the immune system in which various components of the immune defense may be impaired. The term PID encompasses numerous different disorders, which are classified based on the part of the immune system affected. Among the most common forms are IgA deficiency, common variable immunodeficiency (CVID), agammaglobulinemia (Bruton’s disease), and severe combined immunodeficiency (SCID). Normally, a functioning immune system protects the body from various pathogens—such as bacteria, viruses, and fungi—by recognizing and fighting them. If this defense function is disrupted by defects—because parts of the immune system are missing or do not work properly—it can lead to frequent and severe infections. These defects can also trigger severe immune system reactions directed against the body itself (autoimmune reactions) or cause chronic inflammation due to a prolonged, uncontrolled immune response. Thus, germs that are harmless to healthy people can become dangerous for people with PID and result in organ damage due to chronic inflammation. To prevent this, early diagnosis is essential. However, due to the wide range of symptoms, nonspecific complaints, the rarity of these disorders, and the specialized diagnostic procedures required, PID is often not diagnosed until late in life.

The standard treatment for PID depends on the type of defect and includes immunoglobulin therapy to replace missing antibodies, as well as antibiotics or antiviral medications to treat or prevent infections (prophylaxis). In severe cases, a stem cell transplant can restore the immune system. In rare cases, gene therapy can correct the underlying defect. Early initiation of treatment is crucial, as untreated PIDs can lead to severe infections, organ damage, or autoimmune diseases. Timely treatment can prevent complications, improve quality of life, and, in some cases, lead to a cure.

The goal of the ESID Registry Study is to consolidate clinical and laboratory data into a single registry. This data will be collected and analyzed to improve diagnostic accuracy, classification, prognosis assessment, and—in the future—the treatment of these diseases. To this end, data on the participant’s medical history to date will be recorded upon registration (retrospectively). In addition, long-term follow-up (prospectively) will be conducted as part of the study. New findings regarding the individual’s condition could influence treatment; however, this will not occur within the scope of this registry study. No treatment is being tested or prescribed in the study; this is purely an observational registry study.

Anyone diagnosed with a primary immunodeficiency can participate in the study. There are no age restrictions.