Primary Immune Deficiency (PID) refers to a group of disorders caused by genetic defects that impair the immune system's ability to function properly. Individuals with PID are more susceptible to infections, autoimmune diseases, and certain cancers due to their weakened immune response. These conditions can affect various components of the immune system, including B cells, T cells, and antibodies. Diagnosis of PID often involves blood tests to assess immune function and genetic testing to identify specific defects. Treatment may include immunoglobulin therapy, antibiotics, and in some cases, bone marrow transplants to help restore immune function. Early detection and management are crucial for improving the quality of life for those affected.